7th Std Science Lesson Wise Questions in English – Part 1

7th Std Science Lesson Wise Questions in English

7th Science Lesson 1 Questions in English

1] Measurement

1. Which among the following is not the physical quantities?

Mass
Distance
Temperature
None of the above

Explanation

In day-to-day life, we measure many things such as the weight of fruits, vegetables, food grains, volume of liquids, temperature of the body, speed of the vehicles etc., Quantities such as mass, weight, distance, temperature, volume are called physical quantities.

2. Which among the following is not the classification of physical quantities?

Fundamental quantities
Derived quantities
Logistic quantities
None of the above

Explanation

Generally, physical quantities are classified into two types, namely, (i) Fundamental quantities and (ii) Derived quantities.

3. Which among the following statement is correct

A set of physical quantities which cannot be expressed in terms of any other quantities are known as “Derived quantities”. Their corresponding units are called “Derived units”.
All other derived quantities which can be obtained by multiplying, dividing or by mathematically combining the derived quantities are known as “Fundamental quantities”. Their corresponding units are called “Fundamental units.
Only 1
Only 2
Both 1 and 2
None

Explanation

A set of physical quantities which cannot be expressed in terms of any other quantities are known as “Fundamental quantities”. Their corresponding units are called “Fundamental units”.

All other physical quantities which can be obtained by multiplying, dividing or by mathematically combining the fundamental quantities are known as “derived quantities”. Their corresponding units are called “Derived units”.

4. Which among the following is the Derived unit of Area?

m
m²
m³
None of the above

Explanation

The area is a measure of how much space there is on a flat surface. The area of the plot of land is derived by multiplying the length and breadth

Area = length × breadth

The unit of the area is = metre × metre

= metre²

= m² (Read as square metre).

Area is a derived quantity as we obtain are by multiplying twice of the fundamental physical quantity length

5. Which among the following is the Fundamental unit of Luminous (light) intensity?

Mole
Ampere
Candela
Kelvin

Explanation

Length – Metre (m); Mass – Kilogram (kg); Time – Second (s); Temperature – Kelvin (K); Electric current – Ampere (A); Amount of substance – Mole (Mol); Luminous (light) intensity – Candela (cd).

6. Which among the following is the derived unit of Electric charge?

square metre (or) m²
cubic metre (or) m³
kg m^-3
Coulomb (C)

Explanation

Area = length × breadth – m × m = square metre (or) m²; Volume = length × breadth × height – m × m × m = cubic metre (or) m³; Speed = distance / time – m / s (or) m s^-1; Electric charge = electric current × time – A × s = As (or) Coulomb (C); Density = mass / volume – Kg / m³ (or) kg m^-3.

7. What is the area of 10 squares each of side of 1 m?

1 square metre
10 square metre
100 square metre
0.1 square metre

Explanation

Area of a square = side × side

= 1 m × 1 m = 1 m² or 1 square metre

Area of 10 squares = 1 square metre × 10

= 10 square metre

(Even though the area is given in square metre, the surface need not to be square in shape).

8. Which among the following is the area of Triangle?

a²
lb
πr²
× b × h

Explanation

Square = side × side = a × a = a²; Rectangle = length x breadth = l x b=lb; Circle = π ×(radius)² = π ×r² =πr²; Triangle = (1/2) × base × height = 1/2 × b × h.

9. The area of such irregularly shaped figures can be calculated using what?

Formula
Graph sheet
Linear line
None of the above

Explanation

In our daily life, we encounter many irregularly shaped figures like leaves, maps, stickers of stars or flowers, peacock feather etc. The area of such irregularly shaped figures cannot be calculated using any formula. We can find the area of these figures with the help of a graph sheet.

10. Find the area of the following regular shaped figures: (Take π = 22/7)

(i) A rectangle whose length is 12 m and breadth is 4 m

(ii) A circle whose radius is 7 m.

(iii) A triangle whose base is 6 m and height is 8 m

3m, 22m, 48m²
48m², 22m, 48m²
48 m^2,154 m², 24 m²
16m², 154m², 24m²

Explanation

(i) Area of rectangle = length × breadth = 12 × 4 = 48 m²

(ii) Area of circle = π × r2 = (22/7) × 7 × 7 = 154 m²

(iii) Area of triangle = (1/2) × base × height = (1/2) × 6 × 8 = 24 m²

11. The amount of space occupied by a three-dimensional object is known as its ____

Area
Surface area
Breadth
Volume

Explanation

The amount of space occupied by a three-dimensional object is known as its volume. volume = surface area × height.

12. The SI unit of volume is __________

m^-2
m²
m³
m^-3

Explanation

The SI unit of volume is cubic metre or m³. As in the case of area, the volume of the regularly shaped objects can also be determined using an appropriate formula.

13. Which among the following is the formula used to find volume of cuboid?

a³
l × b × h
π r³
π r² h

Explanation

The volume of Cuboid is length × breadth × height = l × b × h = l b h.

14. Which among the following is the formula used to find volume of cylinder?

a³
l × b × h
π r³
π r² h

Explanation

The volume of cylinder is π × (radius)² × height = π ×r²×h = π r² h.

15. Find the volume of (Take π = 22/7)

i. a cube whose side is 3 cm

ii. a cylinder whose radius is 3 m and height is 7 m.

9 cm³,198 m³
9 cm³, 66 m³
27 cm³, 198 m³
27 cm³, 66 m³

Explanation

(i) Volume of a cube = side × side × side = 3 cm × 3 cm × 3 cm = 27 cubic cm or cm³.

(b) Volume of a cylinder = π × r² × height = (22/7) × 3 × 3 × 7 = 198 m³

16. Which among the following is the formula used to find the volume of sphere?

a³
l × b × h
π r³
π r² h

Explanation

The volume of the sphere is 4/3 × π × (radius)³ = 4/3 × π ×r³ = π r³.

The volume of cube is a³.

17. Which among the following statement is correct

Liquids also occupy some space and hence they also have volume. But liquids do not possess any definite shape. So, the volume of a liquid cannot be determined as in the case of solids. When a liquid is poured into a container, it takes the shape and volume of the container.
The volume of any liquid is equal to the space that it fills and it can be measured using a measuring cylinder or measuring beaker. The maximum volume of liquid that a container can hold is known as the “capacity of the container”. The volume of a liquid is equal to the volume of space it fills in the container. This can be directly observed from the readings marked in the measuring containers.
To understand this unit of volume, let us first understand how much a litre means. Litre is the commonly used unit to measure the volume of liquids. we can understand that the unit of volume is cubic cm if the dimensions of the object are given in cm. This cubic cm is commonly known as cc. A volume of 100 cc is termed as one litre (l). 1 litre = 100 cc or cm3 100 ml = 1 litre.
Both 1 and 2
Both 1 and 3
Both 2 and 3
All 1, 2 and 3

Explanation

To understand this unit of volume, let us first understand how much a litre means. Litre is the commonly used unit to measure the volume of liquids. we can understand that the unit of volume is cubic cm if the dimensions of the object are given in cm. This cubic cm is commonly known as cc. A volume of 1000 cc is termed as one litre (l). 1 litre = 1000 cc or cm3 1000 ml = 1 litre.

18. Which among the following is not the unit to measure the volume of liquids?

Gallon
Ounce
Quart
Pascal

Explanation

To measure the volume of liquids, some other units are also used. Some of them are gallon, ounce, and quart.

19. Which among the following is the value of 1 gallon?

2482 ml
3785 ml
4824 ml
1893 ml

Explanation

1 gallon = 3785 ml.

20. Which is defined as the mass of the substance contained in unit volume (1 m³)?

Surface area
Quarts
Density
Mole

Explanation

Density of a substance is defined as the mass of the substance contained in unit volume (1 m³).

21. Which among the following is the equation of density?

D = M V
D =
D =
D = M+V

Explanation

If the mass of a substance is “M” whose volume is “V”, then, the equation for density is given as

Density (D) = =

22. What is the SI unit of density?

Kg m
Kg/m
Kg/m²
Kg/m³

Explanation

The SI unit of density is kg/m³.

23. The CGS unit of density is ___________

g/m³
g/cm³
kg/cm³
kg/m³

Explanation

The CGS unit of density is g/cm³.

24. The materials with lower density are called _______

Denser
Rarer
Pitcher
Glitter

Explanation

Different materials have different densities. The materials with higher density are called “denser” and the materials with lower density are called “rarer”.

25. Which among the following material has higher density?

Air
Kerosene
Water
Mercury

Explanation

Air – 1.2 kg/m³, Kerosene – 800 kg/m³, Water – 1000 kg/m³, mercury – 13600 kg/m³.

26. What is the density of wood?

770 kg/m³
1200 kg/m³
1780 kg/m³
2190 kg/m³

Explanation

The density of wood is 770 kg/m³.

27. Which among the following material has higher density?

Gold
Copper
Silver
Iron

Explanation

Iron – 7800 kg/m³, Copper – 8900 kg/m³, Silver – 10500 kg/m³, Gold – 19300 kg/m³.

28. A solid cylinder of mass 280 kg has a volume of 4 m³. Find the density of cylinder?

1040 kg m³
70 kg/m³
284 kg m³
None of the above

Explanation

Density of cylinder = = = 70 Kg/m³.

29. A box is made up of iron and it has a volume of 125 cm³. Find its mass. (Density of iron is 7.8 g / cm³).

16.02 cm⁶ g^-1
7.605 kg
975 g
None of the above

Explanation

Density = Mass / Volume

Hence, Mass = Volume × Density = 125 × 7.8 = 975 g.

30. Which among the following equation is incorrect

Density = Mass × Volume
Mass = Density / Volume
Volume = Density / Mass
Both 1 and 2
Both 1 and 3
All the above
None of the above

Explanation

Density = Mass/ Volume

Mass = Density × Volume

Volume = Mass / Density

31. A sphere is made from copper whose mass is 3000 kg. If the density of copper is 8900 kg/m³ , find the volume of the sphere.

0.34 m³
2.96 m^-3
11,900 kg/m³
None of the above

Explanation

Density = Mass / Volume

Hence, Volume = Mass / Density

= 3000 / 8900 = 30 / 89 = 0.34 m³.

32. Which among the following is the unit used in space research by astronomers to measure very long distances such as the distance between the earth and a star or the distance between two stars?

Astronomical unit
Celestial point
Conjunction unit
All the above

Explanation

Normally, we use centimetre, metre and kilo metre to express the distances that we measure in our day-to-day life. But, for space research, astronomers need to measure very long distances such as the distance between the earth and a star or the distance between two stars. To express these distances, we shall learn about two such units, namely, i. Astronomical unit ii. Light year.

33. What is the density of castor oil?

748 kg/m³
892 kg/m³
961 kg/m³
1038 kg/m³

Explanation

Water has more density than oils like cooking oil and castor oil, although these oils appear to be denser than water. Density of castor oil is 961 kg/m³. If we put one drop of water in oil, water drop sinks. But, if we put one drop of oil in water, oil floats and forms a layer on water surface. However, some oils are denser than water.

34. Which is position of the shortest distance between the earth and the sun?

aphelion position
Perihelion position
Proxima position
Kepler position

Explanation

We all know that the earth revolves around the sun in an elliptical orbit. Hence, the distance between the sun and the earth varies every day. Perihelion is position of the shortest distance between the earth and the sun.

35. What is the distance between sun and earth in perihelion position?

122.3 million kilometres
138.6 million kilometres
147.1 million kilometres
158.9 million kilometres

Explanation

When the earth is in its perihelion position (Perihelion is position of the shortest distance between the earth and the sun), the distance between the earth and the sun is about 147.1 million kilometres.

36. Which is the position of farthest distance between the earth and the sun?

aphelion position
Perihelion position
Proxima position
Kepler position

Explanation

When the earth is in its farthest position, that is when the distance between Earth and Sun is the largest it is called aphelion position.

37. What is the distance between sun and earth in aphelion position?

149.4 million kilometres
152.1 million kilometres
158.6 million kilometres
163.9 million kilometres

Explanation

When the earth is in its farthest position, that is when the distance between Earth and Sun is the largest (called aphelion position) the distance is 152.1 million kilometres.

38. Th e average distance between the earth and the sun is about _______

143.4 million kilometres
149.6 million kilometres
151.4 million kilometres
153.7 million kilometres

Explanation

The average distance between the earth and the sun is about 149.6 million kilometres. Th is average distance is taken as one astronomical unit. One astronomical unit is defi ned as the average distance between the earth and the sun.

1 AU = 149.6 million km = 149.6 × 10⁶ km = 1.496 × 10¹¹ m.

39. What is the distance of Neptune from the sun?

12 AU
26 AU
30 AU
42 AU

Explanation

Neptune is 30 AU away from the Sun. It means it is thirty times farther than the Earth.

40. The nearest star to our solar system is ____________

Alpha Centauri
Proxima Centauri
Sirius
Betelgeuse

Explanation

The nearest star to our solar system is Proxima Centauri. It is at a distance of 2,68,770 AU.

41. We can clearly see that using the AU for measuring distances of stars would be unwieldy. Therefore, astronomers use a special unit, called _________

Light year
Astronaut year
Century year
Sirius year

Explanation

We can clearly see that using the AU for measuring distances of stars would be unwieldy. Therefore, astronomers use a special unit, called ‘light year’, for measuring the distance in deep space. One light year is defined as the distance travelled by light in vacuum during the period of one year.

42. What is the speed of light in vacuum?

1.2 × 10⁸ m
3 × 10⁸ m
4.2 × 10⁸ m
5 × 10⁸ m

Explanation

We, have learnt that the speed of light in vacuum is 3 × 108 m/s. Th is means that light travels a distance of 3 × 10⁸ m in one second.

43. What is the value of 1 light year?

9.46 × 10¹⁵ m
10.13 × 10¹⁵ m
14.62 × 10¹⁵ m
19.31 × 10¹⁵ m

Explanation

In a year (non-leap), there are 365 days. Each day has 24 hours; Each hour has 60 minutes; Each minute has 60 seconds. Th us, the total number of seconds in one year = 365 × 24 × 60 × 60 = 3.153 × 10⁷ second.

If light travels a distance of 3 × 108 m in one second, then the distance travelled by light in one year = 3 × 10⁸ × 3.153 × 10⁷ = 9.46 × 10¹⁵ m. This distance is known as one light year.

1 Light year = 9.46 × 10¹⁵ m.

44. In terms of light year, Proxima Centauri is at what distance from Earth and the Solar System (and Earth)?

1.72 light-years
2.91 light-years
4.22 light-years
6.18 light-years

Explanation

In terms of light year, Proxima Centauri is at 4.22 light-years from Earth and the Solar System (and Earth).

45. The Earth is located about how many light-years away from the galactic centre?

12000 light-years
18000 light-years
20000 light-years
25000 light-years

Explanation

The Earth is located about 25,000 light-years away from the galactic centre.

46. What is the value of 1 ounce of liquid?

15 ml
30 ml
42 ml
58 ml

Explanation

1 ounce = 30 ml; 1 quart = 1 litre

7th Science Lesson 2 Questions in English

2] Force and Motion

1. The shortest distance from the initial to the final position of an object is called _____

Projectile
Velocity
Transient
Displacement

Explanation

The shortest distance from the initial to the final position of an object is called Displacement.

2. Which among the following statement is correct

When an object travels from one place to another, it will reach slower if it travels along the straight-line path. The straight-line path is the longest distance between two points.
The total length of a path taken by an object to reach one place from the other is called distance.
Only 1
Only 2
Both 1 and 2
None

Explanation

When an object travels from one place to another, it will reach faster if it travels along the straight-line path. The straight-line path is the shortest distance between two points.

3. What is the SI unit of displacement?

m
m/s
m s^-2
kg/s

Explanation

Both the distance and displacement possess the same unit. The SI unit is meter (m).

4. The path of an object travelling from A to B is shown in figure

What is the displacement of the object?

40 m
80 m
120 m
160 m

Explanation

The path of an object travelling from A to B is shown in figure. Total distance travelled by the object is 120 m. The displacement of the object is 40 m (south-east direction). Here we can consider the starting point as A and while the object moves from A to B the displacement is considered to be positive and from B to A it is negative.

5. Convert 1 km/hr in m/s?

2/28 m/s
3/19 m/s
5/18 m/s
7/12 m/s

Explanation

1 km/h = 5/18 m/s

1 km = 1000 m; 1 h = 3600 s

1 km / h = 1000 m / 3600 s = 5/ 18 m /s.

6. Which among the following equation is correct?

Speed = distance / time
Speed = time / distance
Speed = distance × time
None of the above

Explanation

Speed is the rate of change of distance. Speed = distance /time Unit is metre/second (m/s).

7. Which among the following statement is incorrect

We can classify speed into two types. If a body in motion covers equal distances in equal intervals of time, then the body is said to be in uniform speed.
If a body covers unequal distances in equal intervals of time, the body is said to be in nonuniform speed. Average speed = time taken to travel the distance/ total distance travelled.
Only 1
Only 2
Both 1 and 2
None

Explanation

If a body covers unequal distances in equal intervals of time, the body is said to be in nonuniform speed. Average speed = total distance travelled / time taken to travel the distance.

8. Which among the following equation is correct?

Velocity = speed × displacement
Velocity = displacement × time
Velocity = displacement/time
Velocity = speed / displacement

Explanation

Velocity is the rate of change in displacement. Velocity (v) = displacement / time.

9. If an athlete in the diagram takes 25 s to complete a 200 m sprint event. Find her speed and velocity.

speed = 8 m/s, velocity = 2 m/s
speed = 4 m/s, velocity = 2 m/s
speed = 2 m/s, velocity = 8 m/s
speed = 8 m/s, velocity = 4 m/s

Explanation

Speed = distance / time = 200 / 25 = 8 m/s

velocity = displacement /time = 50 / 25 = 2 m/s.

10. What is the SI unit of Velocity?

m
m s
m/s
m/s²

Explanation

SI unit of velocity is meter / second (m/s).

11. A light travels through vacuum is example of which velocity?

Uniform velocity
Reverse velocity
Non-Uniform velocity
All the above

Explanation

A body has uniform velocity, if it covers equal displacement in the same direction in equal intervals of time. E.g., light travels through vacuum.

12. A train starting and moving out of the station is example of which velocity?

Uniform velocity
Reverse velocity
Non-Uniform velocity
All the above

Explanation

If either speed or direction changes, the velocity is non uniform. E.g., a train starting and moving out of the station.

13. Which among the following equation is correct?

Average velocity = total displacement / total time taken
Average velocity = average displacement / average time taken
Average velocity = average speed / average time taken
Average velocity = average displacement / average speed

Explanation

Average velocity = total displacement / total time taken.

14. Figure shows a car that travels 5 km due east and makes a U – turn to travel another 7 km. If the time taken for the whole journey is 0.2 h. Calculate the average velocity of the car.

0.17 m/s
0.28 m/s
– 0.17 m/s
– 0.28 m/s

Explanation

Average velocity = total displacement/time taken. (taking the direction due east of point O as positive)

= (5 – 7) / 0.2 = –2 / 0.2

= –10 km/h (or) –10 × 5/18 = 25/9

= – 0.28 m/s

15. Which among the following relation is incorrect?

v = d / t
t = d / v
d = v × t
None of the above

Explanation

The triangle method can help you to recall the relationship between velocity (v), displacement (d), and time(t). v = d / t, t = d / v, d = v × t.

16. Which is the rate of change in velocity?

Optimization
Conjunction
Acceleration
Polarisation

Explanation

Acceleration is the rate of change in velocity. In other words, if a body changes its speed or dirction then it is said to be accelerated.

17. Which among the following equation is correct

a = (u–v) / t
a = (v–u) / t
a = (v–u) × t
a = v / (u × t)

Explanation

Acceleration = change in velocity/ time

= [final velocity (v) – initial velocity (u)] / time (t)

a = (v–u) / t.

In other words, the object undergoes acceleration when its speed and/or direction change(s).

18. Which among the following is the SI unit of acceleration?

m
m/s
m/s²
m s

Explanation

SI unit of acceleration is m/s².

19. A car at rest starts to travel in a straight path. It reaches a velocity of 12 m/s in 4 s . What is its acceleration. Assuming that it accelerates uniformly?

12 m s
12 m/s
3 m/s
3 m/s²

Explanation

Initial velocity u = 0 m/s (since the car starts from rest)

Final velocity (v) = 12 m /s

Time taken (t) = 4 s

acceleration (a) = (v – u) / t

= (12 – 0) / 4

= 3 m / s²

20. If the velocity of an object increases with respect to time, then the object is said to be in ___

Retardation
Just acceleration
Deceleration
All the above

Explanation

If the velocity of an object increases with respect to time, then the object is said to be in positive acceleration or just acceleration.

21. If the velocity of an object decreases with respect to time, then the object is said to be in ___

Retardation
Deceleration
Negative acceleration
All the above

Explanation

If the velocity of an object decreases with respect to time, then the object is said to be in negative acceleration or deceleration or retardation.

22. Th e velocity of a golf ball rolling in a straight-line change from 8 m/s to 2 m/s in 10 s. What is its deceleration, assuming that it is decelerating uniformly?

– 0.6 m/s²
– 2 m/s²
0.6 m/s²
2 m/s²

Explanation

Initial velocity (u) = 8 m/s

Final velocity (v) = 2 m/s

Time taken(t) = 10 s

Acceleration (a) = (v – u)/t = (2 – 8)/10 = –0.6 m/s²

The deceleration is –0.6 m/s.

23. Which among the following statement is correct

An object undergoes uniform acceleration when the change (increase or decrease) in its velocity for every unit of time is the same. When the velocity of the object is increasing by 20 m/s the acceleration is 20 m/s². When the velocity of the object is decreasing by 20 m/s the deceleration is 20 m/s².
An object undergoes non uniform acceleration if the change in its velocity for every unit of time is not the same. Note that the change in velocity is same for every second. The moving object is undergoing non uniform acceleration.
Only 1
Only 2
Both 1 and 2
None

Explanation

An object undergoes non uniform acceleration if the change in its velocity for every unit of time is not the same. Note that the change in velocity is not the same for every second. Th e moving object is undergoing non uniform acceleration.

24. Which among the following statement is correct based on the graph?

The graph has zero gradient. The distance is a constant for every second.
The graph has a zero-constant gradient. The distance increases 10 m every second.
The graph has an increasing gradient. The speed increases.
The graph has a decreasing gradient. The speed decreases

25. Which among the following statement is correct based on the graph?

The graph has zero gradient. The distance is a constant for every second.
The graph has a zero-constant gradient. The distance increases 10 m every second.
The graph has an increasing gradient. The speed increases.
The graph has a decreasing gradient. The speed decreases

26. Which among the following statement is correct based on the graph?

The graph has zero gradient. The distance is a constant for every second.
The graph has a zero-constant gradient. The distance increases 10 m every second.
The graph has an increasing gradient. The speed increases.
The graph has a decreasing gradient. The speed decreases.

27. Which is the point through which the entire weight of the object appears to act?

Projectile point
Centre conjoint
Centre of gravity
Centre of active

Explanation

The centre of gravity of an object is the point through which the entire weight of the object appears to act. Try to balance a cardboard on your figure tip. We observe there is only one point which the cardboard is balanced. The point which the cardboard is balanced is called the centre of gravity of the cardboard.

28. Which is a measure of the body’s ability to maintain its original position?

Stability
Integrity
Conductivity
Capacity

Explanation

Stability is a measure of the body’s ability to maintain its original position.

29. Which among the following is not the type of stability?

Stable equilibrium
Unstable equilibrium
Neutral equilibrium
Retarding equilibrium

Explanation

The three types of stability are (a) Stable equilibrium (b) Unstable equilibrium (c) Neutral equilibrium.

30. The following image describes which among the following stability?

Stable equilibrium
Unstable equilibrium
Neutral equilibrium
All the above

Explanation

In this unstable equilibrium the frustum will topple with the slightest tilting. Its centre of gravity is lowered when it is displaced.

31. The following image describes which among the following stability?

Stable equilibrium
Unstable equilibrium
Neutral equilibrium
All the above

Explanation

The vertical line through its centre of gravity falls outside its base. It causes frustum to topple. The frustum will roll about but does not topple. Its centre of gravity remains at the same height when it is displaced. Te body will stay in any position to which it has been displaced.

32. The Thanjavur doll is type of traditional Indian toy made of which material?

Iron
Copper
Terracotta
Ceramic

Explanation

The Thanjavur Doll is type of traditional Indian toy made of terracotta material. Th e centre of gravity and the total weight of the doll is concentrated at its bottom most point, generating a dance-like continuous movement with slow oscillations.

33. Which among the following is not the condition for stability?

Lower its centre of gravity
Lower the area of its base
A heavy base lower at the centre of gravity So the box does not tip over
A broad base makes the box more difficult to tip over

Explanation

To make a body more stable 1. Lower its centre of gravity 2. Increase the area of its base 3. Th is box is at the point of tipping over 4. A heavy base lower at the centre of gravity So the box does not tip over 5. A broad base makes the box more difficult to tip over.

34. The following image describes which among the following stability?

Stable equilibrium
Unstable equilibrium
Neutral equilibrium
All the above

Explanation

The frustum can be tilted through quite a big angle without toppling. Its centre of gravity is raised when it is displaced. The vertical line through its centre of gravity still falls within its base. So it can return to its original position.

7th Science Lesson 3 Questions in English

3] Matter Around Us

1. Which among the following is the matter?

Heat
Light
Sound
Air

Explanation

We knew that everything we see around, that occupy space and have mass, is called matter. Heat, light and sound occupies space, but does not have mass. Hence these are not matter. Air is a matter since it has mass and occupies space.

2. The graphite refill used in pencil is made up of element called _______

Copper
Carbon
Nitrogen
All the above

Explanation

The graphite refill used in pencil is made up of element called Carbon. We can break the graphite into smaller and smaller pieces. In fact, if we have an even finer knife, we can break it even smaller. If keep cutting the minuscule graphite into smaller and smaller particle, we will reach a point where we reach smallest constituent of graphite- carbon atom.

3. The smallest unit of an element that exhibits the properties of the element is called as ______

Dark matter
Atom
Nucleus
Positron

Explanation

The smallest unit of an element that exhibits the properties of the element is called as ‘atom’. All the matter is composed of tiny particles called atom. Water, rice, in short everything we see around is made up of atoms.

4. The most abundant type of atom in the universe is _______

Carbon atom
Oxygen atom
Nitrogen atom
Hydrogen atom

Explanation

The most abundant type of atom in the universe is the hydrogen atom. Nearly 74% of the atoms in the universe are hydrogen atoms. However, on Earth the three most abundant atom are iron, oxygen, and silicon.

5. When an atom combines with another atom (or atoms) and forms a compound it is called as _______

Nucleus
Molecule
Positron
None of the above

Explanation

When an atom combines with another atom (or atoms) and forms a compound it is called as molecule. A molecule is made up of two or more atoms chemically combined.

6. Ozone is a substance that is made up of how many oxygen atoms chemically combined?

Two
Three
Four
Eight

Explanation

Ozone is a substance that is made up of three oxygen atoms chemically combined.

7. Which among the following statement is correct?

Molecules also exhibit properties of matter and have individual existence.
A molecule can be formed by the same kinds of atoms
A molecule can be formed by different kinds of atoms
All the above

Explanation

Molecules also exhibit properties of matter and have individual existence. A molecule can be formed by the same or different kinds of atoms.

8. Oxygen gas in the air that we breathe is made up of how many oxygen atoms chemically combined?

Two
Three
Four
Eight

Explanation

Oxygen gas in the air that we breathe is made up of two oxygen atoms chemically combined.

9. Which among the following is not the monatomic molecule?

Helium
Krypton
Hydrogen
Neon

Explanation

A molecule which contains only one atom is called monatomic molecule (inert gases like helium, neon, xenon, krypton, etc.,

10. Which among the following molecule is not diatomic molecule?

Oxygen
Carbon dioxide
Hydrogen
Nitric oxide

Explanation

A molecule which contains two atoms is called diatomic molecule (oxygen, nitric oxide, hydrogen, etc.).

11. Which among the following is not polyatomic molecule?

Phosphate
Ozone
Sulphur
None of the above

Explanation

A molecule containing more than 3 atoms are known as polyatomic molecule (phosphate, sulphur, etc.).

12. In which among the following state each molecule of water consists of one oxygen atom and two hydrogen atoms remain in this ratio?

Liquid
Solid
Gaseous
All the above

Explanation

Each molecule of water consists of one oxygen atom and two hydrogen atoms. This ratio of oxygen and hydrogen atom remains fixed whether water is in liquid, solid or gaseous state. This principle applies to the molecules of all compounds. Oxygen gas in the air that we breathe is made up of two oxygen atoms chemically combined

13. Which among the following is not triatomic molecule?

Ozone
Sulphur dioxide
Carbon dioxide
None of the above

Explanation

A molecule containing three atoms is called a triatomic molecule (ozone, sulphur dioxide, carbon dioxide, etc.).

14. Which is an element that occurs naturally combined with other elements to make medicine for treating diarrhoea?

Lead
Polonium
Bismuth
Tin

Explanation

Bismuth is an element that occurs naturally. It is combined with other elements to make medicine for treating diarrhoea.

15. matter is classified into how many types?

Two
Three
Four
Six

Explanation

Matter is classified into two broad categories, namely, pure substances and mixtures. Pure substances are further divided into categories as elements and compounds.

16. Which among the following element is not present in common salt?

Sodium
Bromine
Chlorine
None of the above

Explanation

Matter in its simplest form is called an element. We are using many elements in our daily life. The common salt is consisting of elements of Sodium and Chlorine. Water consists of Hydrogen and Oxygen.

17. Which among the following element is not used for making crackers?

Magnesium
Sodium
Phosphorous
None of the above

Explanation

Magnesium and Phosphorus used for making crackers.

18. Which among the following is used as manure in agriculture?

Sodium
Chlorine
Sulphur
Bromine

Explanation

Sulphur is used as manure in agriculture.

19. Which among the following element is used for making computer chips?

Cadmium
Sulphur
Silicon
Fluorine

Explanation

Gallium is used for making mobile phones and silicon is used for making computer chips.

20. How many known elements are there till date?

108
112
118
124

Explanation

There are 118 known elements till date.

21. Elements can be broadly classified into how many types based upon their chemical properties?

Two
Three
Four
Five

Explanation

We can classify the elements broadly into three types metals, non-metals and metalloids based upon their chemical properties.

22. In 118 known elements how many elements occur naturally?

Explanation

There are 118 known elements till date. 94 of these elements occur naturally while 24 elements have been created artificially in the laboratory.

23. Which among the following metal is soft?

Calcium
Sodium
Tin
Zinc

Explanation

Metals are generally hard and shiny elements. Sodium is one of the exceptions as it is soft.

24. Which among the following is the only metal that is liquid at room temperature?

Mercury
Nickle
Magnesium
Zinc

Explanation

All metals, except mercury are solids at room temperature. Mercury is the only metal that is liquid at room temperature.

25. Which among the following statement is correct

We have tools, utensils and jewellery made from silver, copper, iron, gold, Aluminium. Using pressure like hammering or rolling we can deform these materials into various shapes. Such elements that are malleable (a material may be flattened into thin sheets or various shapes) is called as metals.
Metals are generally hard and shiny elements. Metals are malleable, can be bent or beaten into sheets. They can be drawn into wires. They are good conductors of heat and electricity. Copper, Lead, tin, nickel, iron, zinc, gold, magnesium and calcium are examples of metals.
Only 1
Only 2
Both 1 and 2
None

26. Which among the following is shiny and also the hardest natural substance on earth?

Gold
Platinum
Copper
Diamond

Explanation

Non-metals are generally dull and soft. However, diamond is shiny and also the hardest natural substance on earth.

27. Which among the following Non-metal is not solid at room temperature?

Chlorine
Carbon
Iodine
Sulphur

Explanation

Nonmetals can be gases, solids, liquids. Non-metals such as oxygen, hydrogen and chlorine are gases at room temperature. Non-metals such as carbon, iodine, sulphur and phosphorus are solids at room temperature.

28. Which is the only non-metal that is liquid at room temperature?

Graphite
Iodine
Radon
Bromine

Explanation

Bromine is the only non-metal that is liquid at room temperature.

29. Which among the following Non-metal is a good conductor of electricity?

Krypton
Graphite
Radon
None of the above

Explanation

Non-metals are poor conductors of heat and electricity. However, graphite (a form of the non-metal carbon) is a good conductor of electricity.

30. Which among the following is not the example of Metalloids?

Silicon
Fluorine
Arsenic
Boron

Explanation

Metalloids exhibit the properties of both metals and non-metals. Silicon, arsenic, antimony, and boron are some examples of metalloids.

31. Which is a pure substance that is formed when the atoms of two or more elements combine chemically in definite proportions?

Nucleus
Positron
Compound
Mixture

Explanation

A compound is a pure substance that is formed when the atoms of two or more elements combine chemically in definite proportions.

32. Which among the following statement is correct

Compounds exhibit properties entirely different from the properties of their constituent elements. For example, the atoms of the elements hydrogen and oxygen combine chemically in a fixed ratio to form the compound water.
However, water does not have the exact same properties as hydrogen and oxygen. For example, at room temperature water exist as liquid while hydrogen and oxygen exist as gases. Also, oxygen supports fire whereas water is used as a fire extinguisher.
Similarly, common salt (sulphur chloride) is a compound made up of elements sulphur and chlorine. It is used in our food, whereas sulphur and chlorine are poison, are both unsafe for consumption.
Both 1 and 2
Both 1 and 3
Both 2 and 3
All 1, 2 and 3

Explanation

Similarly, common salt (sodium chloride) is a compound made up of elements sodium and chlorine. It is used in our food, whereas sodium and chlorine are poison, are both unsafe for consumption.

33. Which among the following is the property of compounds?

A compound is formed when the constituent elements combine in a fixed or various proportion. The properties of a compound are different from those of its constituent elements. A compound cannot be separated into its constituent elements by chemical methods also.
A compound cannot be broken down by physical methods. This is because a compound is made up of different elements that are chemically combined. Sodium chloride cannot be separated by physical methods such as filtration.
Only 1
Only 2
Both 1 and 2
None

Explanation

A compound is formed only when the constituent elements combine in a fixed proportion. The properties of a compound are different from those of its constituent elements. A compound can be separated into its constituent elements by chemical methods only.

34. Which among the following is not property of metal?

Metals are lustrous. They have a shiny surface generally hard and bendable. Most metals can be bent, beaten into sheets and they can draw into wires.
Most metals are good conductors of electricity and heat. Most metals are making ringing sound when struck. Hence, they are used to make objects like bells.
Only 1
Only 2
Both 1 and 2
None

35. The symbol is usually derived from the name of the element, which is either in English or ___

French
Greece
Latin
German

Explanation

A symbol is an abbreviation or short representation of a chemical element. There is a unique symbol for each element. It represents one atom of the element. The symbol is usually derived from the name of the element, which is either in English or Latin.

36. The symbols of an element are allocated by whom?

ISO
IUPAC
WMO
WTO

Explanation

The symbols of an element are allocated by the International Union of Pure and Applied Chemistry (IUPAC).

37. Who was the first scientist to use the symbols for elements in a very specific sense?

J J Thomson
Rutherford
Niels Bohr
Dalton

Explanation

Dalton was the first scientist to use the symbols for elements in a very specific sense. When he used a symbol for an element, he also meant a definite quantity of that element, that is, one atom of that element.

38. Which among the following is the property of non-metal?

Non-metals are non-lustrous. They have non-shiny surface, generally soft and non-bendable. Non-metals are non-ductile.
Non-metals are bad conductors of electricity and heat. Non-metals does not make any sound when they struck.
Only 1
Only 2
Both 1 and 2
None

39. Who suggested that the symbols of elements be made from one or two letters of the name of the element?

Berzelius
Lavoisier
John Dalton
Cannizzaro

Explanation

Berzelius suggested that the symbols of elements be made from one or two letters of the name of the element.

40. Which among the following statement is correct about assigning symbol to an element?

Chemical symbols usually consist of one or two letters. The symbols of most elements correspond to the first letter (which is capitalized) of their English name. For example, the symbol for oxygen is “O” and that for hydrogen is “H”.
When there is more than one element that begins with the same letter, their symbols take two letters. The first letter is capitalised while the second letter also capitalised. For example, the names of both hydrogen and helium begin with H. So, hydrogen is represented by the symbol H and Helium by HE.
Only 1
Only 2
Both 1 and 2
None

Explanation

When there is more than one element that begins with the same letter, their symbols take two letters. The first letter is capitalised while the second letter has a lower case. For example, the names of both hydrogen and helium begin with H. So, hydrogen is represented by the symbol H and Helium by He.

41. Which among the following is the symbol of chromium?

Explanation

The symbol for carbon is C while the symbols for calcium, chlorine and chromium are Ca, Cl and Cr, respectively.

42. Which among the following is the symbol of gold?

Explanation

The symbols for some elements are derived from their Latin names. For example, the symbol for gold is Au after its Latin name Aurum.

43. The symbols for copper is Cu after its Latin name _____

Cuprum
Cullender
Currach
Cumulus

Explanation

The symbols for copper is Cu after its Latin name Cuprum.

44. The name copper was taken from which place name?

Cuenca
Cuzco
Cyprus
Cordoba

Explanation

In the beginning, the names of elements were derived from the name of the place where they were found for the first time. For example, the name copper was taken from Cyprus. Some names were taken from specific colours. For example, gold was taken from the English word meaning yellow.

45. Which among the following statement is correct

Often, we hear that water is H₂O. This is the chemical formula for water molecule. This means that each molecule of water has two hydrogen atoms combined with one oxygen atom. A chemical formula is a symbolic representation of one molecule of an element or a compound.
It provides information about the elements present in the molecule and the number of atoms of each element. The chemical formula tells us the types of atoms and the number of each type of atom in one molecule of substance.
In water (H₂O) there are 2 hydrogen atoms in water molecule and 1 oxygen atom in water molecule. In Sodium Chloride (NaCl) 1 atom of Sodium and 1 atom of chlorine. In Ammonia (NH₃) 1atom of Nitrogen and 3 atoms of Hydrogen.
Both 1 and 2
Both 1 and 3
Both 2 and 3
All 1, 2 and 3

46. Which among the following is the chemical formula of Glucose?

CH₄
C₆H₁₂O₆
C₂H₄
CH₃OH

Explanation

The symbol of Glucose is C₆H₁₂O₆. It has 6 carbon atoms, 12 Hydrogen atoms 6 oxygen atoms.

47. In chemistry we usually understand what to imply the total number of atoms present in one molecule of an element, compound or a substance?

Atomicity
Autonomy
Atomiser
Atomiton

Explanation

In chemistry we usually understand atomicity to imply the total number of atoms present in one molecule of an element, compound or a substance.

48. Which among the following statement is incorrect

Let we see how to calculate the atomicity of elements. For example, Oxygen exists as a diatomic molecule which means that a molecule of oxygen contains two atoms hence its atomicity is 2.
Similarly, a phosphorus (P₅) molecule contains 5 atoms; a sulphur (S₆) molecule contains 6 sulphur atoms. Hence their atomicity is 5 and 6 respectively.
Only 1
Only 2
Both 1 and 2
None

Explanation

Similarly, a phosphorus (P₄) molecule contains 4 atoms; a sulphur (S₈) molecule contains 8 sulphur atoms. Hence their atomicity is 4 and 8 respectively.

49. What is the atomicity of Sulphuric acid?

Explanation

For molecule containing more than one types of atoms, simply count the number of each atom and that would be its atomicity. For example, a molecule of sulphuric acid (H₂ SO₄) consists of 2 hydrogen atom, 1 sulphur atom and 4 oxygen atoms. Hence e its atomicity is 2+1+4=7.

50. Match the following compounds with its respective chemical formula?

Ethanol – 1. NH₃
Methane – 2. C₂H₆O
Sucrose – 3. C₁₂H₂₂O₁₁
Ammonia – 4. CH₄
3 – 2 – 4 – 1
2 – 4 – 3 – 1
1 – 3 – 2 – 4
3 – 1 – 2 – 4

Explanation

H₂O – Water; C₆H₁₂O₆ – Glucose; C₂H₆O – Ethanol; NH₃ – Ammonia; CH₄ – Methane; C₁₂H₂₂O₁₁ – Sucrose.

51. The molecules of which two different elements, make up about 99% of the air?

Hydrogen and Oxygen
Hydrogen and Nitrogen
Nitrogen and Oxygen
Oxygen and Helium

Explanation

Air is a mixture of gases. The molecules of two different elements, nitrogen and oxygen, make up about 99% of the air. The rest includes small amounts of argon and carbon dioxide. (Other gases such as neon, helium, and methane are present in trace amounts.).

52. Which is the lifegiving element in the air?

Carbon dioxide
Helium
Methane
Oxygen

Explanation

Oxygen is the lifegiving element in the air.

53. Who is the first scientist used the term element?

Robert Boyle
Antoine Lavoisier
Robert Hooke
John Dalton

Explanation

The Robert Boyle is the first scientist used the term element. An early proponent of the elemental nature of matter and the nature of vacuum. He was known best for Boyle’s Law.

54. When solid is heated, the particles gain energy and vibrate vigorously. The particles move slightly further apart from one another. This causes the volume of matter to increase. This process is called ?

Conservation
Separation
Expansion
All the above

Explanation

When solid is heated, the particles gain energy and vibrate vigorously. The particles move slightly further apart from one another. This causes the volume of matter to increase. This process is called expansion. The matter begun to expand when heated. The volume increases due to the greater distance between the particles. But the size of the particles remains in same size.

55. When air inside the hot air balloon is heated with a burner, it expands. The expansion causes the density of the air inside the balloon to ___________

Increase
Decrease
Remains same
None of the above

Explanation

When air inside the hot air balloon is heated with a burner, it expands. The expansion causes the density of the air inside the balloon to decrease. Hence, the air inside the balloon has a lower density that the air outside of the balloon. This difference is density allows the hot-air balloon to float.

56. Which among the following statement is correct

During heating or expansion, the mass of matter does not change. This is explained in the following way. During heating, the distance between the particles of the iron locks change. Mass is conserved when matter expands. Although, the volume of the matter changes, the size and number of the particles of matter do not change.
Hence, during heating, the mass of a matter is conserved. For example, in an iron lock the distance between the iron particles decreased when they gain enough heat. However, the number of iron particles does not change. Hence the mass of the iron lock is conserved.
The melting of ice is an example of a change in the states of matter. The change in the states of matter occurs during melting, boiling and freezing and condensation. When the particles possess enough energy, they overcome the strong forces of attraction between one another. The particles break free from one another and move randomly.
Both 1 and 2
Both 1 and 3
Both 2 and 3
All 1, 2 and 3

Explanation

Hence, during heating, the mass of a matter is conserved. For example, in an iron lock the distance between the iron particles increases when they gain enough heat. However, the number of iron particles does not change. Hence the mass of the iron lock is conserved.

57. At what temperature the liquid water is heated, it boils to become steam?

56⁰C
72⁰C
89⁰C
100⁰C

Explanation

When solid ice is heated to 0⁰ C, it melts to become liquids water. In the same way, liquid water is heated to 100⁰ C, it boils to become steam.

7th Science Lesson 4 Questions in English

4] Atomic Structure

1. What is an average diameter of atom?

1×10^-2 m
1×10^-4 m
1×10^-7 m
1×10^-10 m

Explanation

An atom is one and thousand times smaller than the thickest human hair. It has an average diameter of 0.0000000001m or 1×10^-9 m.

2. Who proposed the atomic theory in the year 1808?

Rutherford
Chadwick
John Dalton
J. J. Thomson

Explanation

John Dalton proposed the atomic theory in the year 1808. He proposed that matter consists of very small particles which he named atoms.

3. One nanometre is equal to __________

1×10^-9 m
1×10^-10 m
1×10⁹ m
1×10¹⁰ m

Explanation

Nanometre is the smallest unit used to measure small lengths. One metre is equal to 1×10⁹ nm or one nanometre is equal to 1×10^-9 m.

4. John Dalton proposed atom is smallest indivisible particle and in what shape?

Cylindrical
Square
Spherical
Trapezium

Explanation

John Dalton proposed an atom is smallest indivisible particle, it is spherical in shape. His theory does not propose anything about the positive and negative charges of an atom.

5. Who proposed different atomic theory in 1897 and compared an atom to a watermelon?

Rutherford
Chadwick
J. J. Thomson
Goldstein

Explanation

In 1897 J.J Thomson proposed a different theory. He compared an atom to a watermelon.

6. Which among the following statement is correct

J. J. Thomson theory proposed that the atom has negatively charged part like the red part of the watermelon and in it are embedded, like the seeds, positively charged particles which he called protons.
According to this theory as the positive and negative charges are equal, the atom as a whole does not have any resultant charge. Thomson’s greatest contribution was to prove by experimentation the existence of the negatively charged particles or electrons in an atom.
Only 1
Only 2
Both 1 and 2
None

Explanation

J. J. Thomson theory proposed that the atom has positively charged part like the red part of the watermelon and in it are embedded, like the seeds, negatively charged particles which he called electrons.

7. Who conducted an experiment bombarded a very thin layer of gold with positively charged alpha rays?

J. J. Thomson
Goldstein
James Chadwick
Rutherford

Explanation

There were short coming in Thomson’s theory, Earnest Rutherford gave a better understanding. Earnest Rutherford conducted an experiment. He bombarded a very thin layer of gold with positively charged alpha rays.

8. Which among the following statement is correct

Rutherford bombarded a very thin layer of gold with positively charged alpha rays. He found that most of these rays which travel at a great velocity passed through the gold sheet without encountering any obstacles. A few are, however, turned back from the sheet.
Based on this experiment, Rutherford proposed his famous theory. In his opinion, – The fact that most alpha particles pass through the gold sheet means that the atom consists mainly of electron in it.
The part from which the positively charged particles are turned back is positively charged but very small in size as compared to the empty space.
Both 1 and 2
Both 1 and 3
Both 2 and 3
All 1, 2 and 3

Explanation

Based on this experiment, Rutherford proposed his famous theory. In his opinion, – 1. The fact that most alpha particles pass through the gold sheet means that the atom consists mainly of empty space.

9. Which among the following is not the theory proposed by Rutherford

The nucleus at the centre of the atom has the positive charge.
Most of the mass of the atom is concentrated in the electrons.
The negatively charged electrons revolve around the nucleus in specific orbits.
In comparison with the size of the atom, the nucleus is very, very small.

Explanation

Rutherford’s theory proposes that 1. The nucleus at the centre of the atom has the positive charge. Most of the mass of the atom is concentrated in the nucleus. 2. The negatively charged electrons revolve around the nucleus in specific orbits. 3. In comparison with the size of the atom, the nucleus is very, very small.

10. Which among the following is not the Subatomic Particle?

Proton
Electron
Nucleus
Neutron

Explanation

The discoveries made during the twentieth century proved that atoms of all elements are made up of smaller components – electron, proton and neutron. An electron from hydrogen atom is no different from electron of a carbon atom. In the same manner, protons and neutrons of all elements also have same characteristics. These, particles that make up the atom are called Subatomic Particles.

11. Which among the following particle is present in nucleus?

Only proton
Proton and Electron
Only Electron
Proton and Neutron

Explanation

The proton is the positively charged particle and its located in the nucleus. Its positive charge is of the same magnitude as that of the electron’s negative charge. Neutron is inside the nucleus.

12. Which revolve around the nucleus of the atom in specific orbits?

Proton
Electron
Positron and proton
Both proton and neutron

Explanation

Electron is a negatively charged particle. Electrons revolve around the nucleus of the atom in specific orbits.

13. The nuclei of all atoms contain neutrons except which one?

Hydrogen
Oxygen
Nitrogen
Helium

Explanation

Neutron is inside the nucleus. The neutron does not have any charge. Excepting hydrogen (protium), the nuclei of all atoms contain neutrons.

14. Protons and Neutrons are the two types of particles in the nucleus of an atom. They are called ___________

Positrons
Nucleons
Magnetron
None of the above

Explanation

Protons and Neutrons are the two types of particles in the nucleus of an atom. They are called nucleons.

15. Which among the following statement is correct

The total negative charge of all an electron outside the nucleus is less than the total positive charge in the nucleus.
The total negative charge of all an electron outside the nucleus is equal to the total positive charge in the nucleus.
The total negative charge of all an electron outside the nucleus is more than total positive charge in the nucleus.
The total negative charge of all an electron outside the nucleus where there is only one positive charge in the nucleus.

Explanation

The total negative charge of all an electron outside the nucleus is equal to the total positive charge in the nucleus. That makes the atom electrically neutral.

16. Which among the following particle is not correctly matched with its scientist who discovered?

Proton – Dalton
Electron – J. J. Thomson
Neutron – Rutherford
Only 1
Both 1 and 2
Both 1 and 3
All 1, 2 and 3

Explanation

Proton(p) – Ernest Rutherford

Electron(e) – Sir John Joseph Thomson

Neutron(n) – James Chadwick

17. What is the mass of proton?

1.5298 ×10^-27kg
1.6726 ×10^-27kg
4.8173 ×10^-27 Kg
9.1093 × 10^-27 kg

Explanation

The mass od proton is 1.6726 ×10^-27. Its charge is +1.

18. What is the mass of Electron?

1.6749 ×10^-31kg
3. 761 ×10^-31 kg
4.8173 ×10^-31 Kg
9.1093 × 10^-31 kg

Explanation

The mass of Electron is 9.1093 × 10^-31. The charge of electron is –1.

19. The number of electrons or protons in an atom is called _________

Mass number
Atomic number
Nuclei number
All the above

Explanation

The number of electrons or protons in an atom is called the atomic number of that atom.

20. What is the mass of neutron?

1.6749 ×10^-27kg
3. 761 ×10^-27 kg
4.8173 ×10^-27 Kg
9.1093 × 10^-27 kg

Explanation

The mass of Neutron is 1.6749 × 10^-27kg. The charge of neutron is 0 i.e., no charge.

21. The Atomic number is represented by which letter?

Explanation

The atomic number is represented by the letter Z. if we know the atomic number of an atom, we know the number of electrons or protons in it.

22. What is the atomic number of Oxygen?

Explanation

In the Oxygen atom there are eight protons and eight electrons in orbit around the nucleus, so the atomic number of helium is z=8.

23. Which is equal to the sum of the number of protons(p) and neutrons (n) in the nucleus?

Mass number
Atomic number
Nuclei number
All the above

Explanation

Mass number is equal to the sum of the number of protons(p) and neutrons (n) in the nucleus.

Atomic mass or mass number = Number of Protons + Number of Neutrons

24. The mass of an atom is concentrated in what?

Neutron
Positron
Nucleus
Electron

Explanation

The mass of an atom is concentrated in its nucleus.

25. The mass number is represented by which letter?

Explanation

The Mass number is represented by letter A.

26. What is the atomic mass number of Lithium (3 Protons and 4 neutrons)?

Explanation

A lithium atom contains 3 Protons and 4 neutrons. Its atomic mass number A = 3+4 = 7.

27. Atoms that have the same mass number but different atomic numbers is known as ____

Isotopes
Isobars
Isometrics
Isotonic

Explanation

Atoms that have the same mass number but different atomic numbers is known as Isobars. for example, Calcium – 40 and Argon – 40.

28. In a sodium atom, there are 11 Protons and 12 neutrons. What is the atomic mass?

Explanation

In a sodium atom, there are 11 Protons and 12 neutrons. Hence, its atomic mass number A = 11 + 12 = 23.

29. Atoms that have same atomic number but different mass numbers is known as _____

Isotopes
Isobars
Isometrics
Isotonic

Explanation

Atoms of the same element can have different number of neutrons. Such atoms will have same atomic number but different mass numbers. These atoms are called isotopes. For example Hydrogen has three isotopes — Hydrogen (₁H¹), Deuterium (₁H²), Tritium (₁H³).

30. In Nitrogen (₇N¹⁴) which is the atomic number?

7
14
21
None of the above

Explanation

7 is the atomic number and 14 is the mass number.

31. Which among the following element is not correctly matched with its mass number?

Hydrogen – 1
Helium – 4
Aluminium – 12
Oxygen – 16

Explanation

32. If the atomic number of sodium is 11 and mass number is 23, then what is the number electron in sodium atom?

Explanation

In an atom no of proton and no of electrons are same i.e., sodium has 11 proton and 11 electrons. So, its atomic number is 11.

33. Some atoms can hold one electron, some can hold two, some can hold three, some can hold four and some cannot hold any electron. This property is called ___________

Isotone
Fusion
Barrer
Valency

Explanation

Some atoms can hold one electron, some can hold two, some can hold three, some can hold four and some cannot hold any electron. This property is called valency.

34. Valency of an atom is measured by its combining property with which among the following atoms?

Helium
Hydrogen
Lithium
Oxygen

Explanation

The combining property of an atom is called as Valency. It is a measure of how many hydrogen atoms it can combine with.

35. What is the valency of Oxygen?

One
Two
Three
Four

Explanation

Oxygen can combine with two hydrogen atoms and create water molecule; the valency of oxygen atom is two.

36. In chlorine, it combines with how many hydrogen atoms to create Hydrochloric acid?

One
Two
Three
Four

Explanation

In case of chlorine, it can combine with only one hydrogen to create HCl (hydrochloric acid) here the valency of chlorine is one.

37. Methane has one carbon atom combining with how many hydrogen atoms?

One
Two
Three
Four

Explanation

Methane has one carbon atom combining with four hydrogen atoms to form carbon molecule is methane (CH4).

38. Which among the following statement is correct

Valency is defined as the combining capacity of an element. Atoms of different elements combine with each other to form molecules. Valency determines the number of atoms of an element that combines with atom or atoms of another type.
Electrons carry a negative electric charge, and protons carry a positive charge. The attraction between them holds electrons in orbits.
Only 1
Only 2
Both 1 and 2
None

39. Which among the following is the Monovalent?

Sodium
Oxygen
Beryllium
Calcium

Explanation

The element having valency one is called monovalent. For example: Hydrogen and Sodium.

40. Which among the following element is present in Banana?

Carbon
Helium
Potassium
Argon

Explanation

Potassium is the element present in Banana. Its atomic number is 19.

41. Which among the following is not the divalent?

Nitrogen
Beryllium
Oxygen
Calcium

Explanation

The elements having valency two are called divalent. For example: Oxygen, calcium and Beryllium.

42. Which among the following is used to fill the balloons that float?

Lithium
Helium
Neon
Fluorine

Explanation

Helium is used to fill the balloon that floats.

43. Which among the following is used in crackers and match sticks?

Neon
Fluorine
Carbon
Phosphorous

Explanation

Phosphorus is used in crackers and match sticks.

44. Which among the following statement is incorrect

When atoms of different elements combine with each other than molecules of compounds are formed. In these instances, it is necessary to know the valency of those elements. For example: 2 Na + Cl₂ ———- 2NaCl

Valency 1 + 1

Here, the valency’s of both sodium and chlorine are 1. Remember The valency of element Na is 1 The valency of element Cl is 1 Then, the molecular formula will be Symbol of Elements NaCl Molecular Formula; Radicals and ions = 1 and 1.
Only 1
Only 2
Both 1 and 2
None

45. Which among the following is the trivalent?

Aluminium
Carbon
Hydrogen
Calcium

Explanation

The elements having valency three are called trivalent. For example: Nitrogen and Aluminium. Some elements exhibit more than one valency. For example: Iron combines with oxygen to form two types ferrous oxide (exhibits valency 2) and ferric oxide (exhibits valency 3).

46. In Mg + Cl2 —🡪- Mg Cl₂. What is the valency of Mg?

Explanation

Here, the valency of magnesium is 2 and that of Cl is 1.

7th Science Lesson 5 Questions in English

5] Reproduction and Modification in Plants

1. Which among the following is not the reproductive organ in plant?

Root
Flower
Fruit
Seed

Explanation

The flowering plants have root, stem and leaves. They are called vegetative organs. Flowers, fruits and seeds in a plant are called reproductive organs.

2. The process by which plants and animals produce young ones and increase their number is known as_____

Fusion
Reproduction
Fission
Combustion

Explanation

The process by which plants and animals produce young ones and increase their number is known as ‘reproduction’.

3. Seed is produced from what by the process of pollination and fertilization?

Leaf
Flower
Root
Stem

Explanation

Seed is produced from a flower by the process of pollination and fertilization. This is known as sexual reproduction.

4. Drumstick can be grown by which reproductive process?

Sexual reproduction
Asexual reproduction
Both Sexual and Asexual
None of the above

Explanation

Drumstick tree can be grown from both seeds and stem cuttings. When plants reproduced from seeds, we call that process as sexual reproduction. All other ways of reproduction without seed are called as asexual reproduction.

5. Which among the following is not the part of flower?

Node
Sepal
Petal
None of the above

Explanation

Node is the part of stem.

6. In a bud, we can see a green colour, leaf like structure which cover the whole bud or flower is called _____________

Petal
Sepal
Stamen
Pistil

Explanation

In a bud, we can see a green colour, leaf like structure which cover the whole bud or flower, each of these green like structure present as an outermost layer is called as sepal.

7. The outermost ring of sepals is called __________

Petals
Calyx
Corolla
Pistil

Explanation

The outer most ring of sepals is known as calyx.

8. Which are the largest part of flowers often attractive, brightly coloured, sometimes sweet scented and attract the insects?

Petals
Stigma
Ovule
Corolla

Explanation

Petals are the largest part of flowers. They are often attractive, brightly coloured, sometimes sweet scented and attract the insects.

9. The ring of petals together is called _______

Stigma
Gynoecium
Corolla
Androecium

Explanation

The ring of petals together is called corolla.

10. Which are arranged on a long tube-like structure inner to the corolla in Hibiscus?

Stamen
Ovule
Pistil
Gynoecium

Explanation

Inner to this corolla, in Hibiscus, we can observe a long tube on which many stamens are arranged.

11. Like stamen in hibiscus, in Datura, we can see only five stalked structures, stamens. This ring or whorl of a flower is called ______

Ovule
Gynoecium
Ovary
Androecium

Explanation

Inner to this corolla, in Hibiscus, we can observe a long tube on which many stamens are arranged. But in Datura, we can see only five stalked structures, stamens. This ring or whorl of a flower is called androecium.

12. Which among the following is not the part of stamens?

Filament
Style
Anther
None of the above

Explanation

Each stamen consists of two parts – a stalk called filament and a lobe called anther. If you touch these lobes in a mature flower, we can get a powdery substance called pollen grains, male reproductive part.

13. The female reproductive part of flower is called?

Stigma
Gynoecium
Corolla
Androecium

Explanation

Inner to this androecium whorl, we can find a female reproductive part of the flower, called Gynoecium.

14. In which part of flower seeds are produced?

Ovary
Style
Stigma
Anther

Explanation

In Gynoecium you will find this part with a swollen bottom part. This is the ovary. Seeds are produced in this part.

15. On top of the ovary there is a slender tube-like structure called ________

Style
Stigma
Ovule
Corolla

Explanation

On top of the ovary there is a slender tube-like structure called style.

16. The top most sticky tip of the style which receive pollen grain is ________

Ovule
Datura
Stigma
Stamen

Explanation

The top most sticky tip of the style is stigma. Pollen grains are received by the stigma. This is the fourth whorl of a flower.

17. A group of flowers arranged together is called _______

Spore
Fragmentation
Inflorescence
Solanaceae

Explanation

A group of flowers arranged together is called inflorescence. Tridax procumbens, looks like a single flower, but is an inflorescence. Leaf juice of this plant is used to cure wounds and cuts.

18. Which is not a single flower but group of flowers clustered together?

Hibiscus
Datura
Sunflower
Lily

Explanation

The sunflower is not a single flower. It is a group of flowers clustered together. A group of flowers arranged together is called inflorescence.

19. Which among the following statement is correct

If all the three whorls- calyx, corolla and stamens are present, then it is called as complete flower. Complete flowers are bisexual flowers. If any of these three whorls is missing, then it is called as an incomplete flower.
Incomplete flowers are unisexual flowers. There are two types of unisexual flowers, male flower and female flower. Th e one with androecium and without gynoecium is called as male flowers and the one with gynoecium and without androecium is known as female flowers.
Only 1
Only 2
Both 1 and 2
None

Explanation

If all the four whorls- calyx, corolla, stamens and pistil are present, then it is called as complete flower. Complete flowers are bisexual flowers. If any of these four whorls is missing, then it is called as an incomplete flower.

20. The process by which pollen grains reach stigma is called as ________

Contamination
Conjunction
Fermentation
Pollination

Explanation

The process by which pollen grains reach stigma is called as pollination. The flower that receives pollen grains is called pollinated flower while the one that did not receive pollen grains is called as unpollinated flower.

21. Which among the following statement is correct

To understand how a flower develops into fruit, let us perform an experiment on pumpkin plant. We know that flowers of pumpkin are unisexual that is some of the flowers are male while many are female flowers. We can easily identify the male and female flower buds of pumpkin, even before they bloom.
Once flower buds appear, immediately identify ten female flower buds. Tie a plastic bag around each bud so that no outside material can enter. Ensure to make small holes with a pin to allow air flow. Wait for two to three days to bloom. Choose three to four male flowers. Pluck the stamens of these flowers and dust the pollen grains in a sheet of paper and collect it.
Open five out of ten bags containing female flowers. Brush the collected pollen grains on the stigma with a soft paint brush. Take care not to damage the stigma. After few days we can see that flower in all bags that were not opened at all would wilt without forming a fruit, while most of the flowers to which pollens have been applied for fruits.
Both 1 and 2
Both 1 and 3
Both 2 and 3
All 1, 2 and 3

22. Agents like Bees, butterflies and others help to carry pollen from one flower to another. Pollen grains stick to their legs, wings or abdomen when they move from one flower to another. This is called as _________

Self-pollination
Cross-pollination
Point pollination
Mixer pollination

Explanation

In some plants like grasses, pollen grains are light. Stamens shed pollen grains, and are carried by wind to another flower. Insects, birds are also other agents of pollination. Bees, butterflies and variety of bird’s hover around flowers. They help to carry pollen from one flower to another. Pollen grains stick to their legs, wings or abdomen when they move from one flower to another. This is called as Cross pollination.

23. Which among the following is not self-pollinate?

Beans
Tomatoes
Paddy
None of the above

Explanation

Beans (Fabaceae), tomatoes (Solanaceae) are commonly self-pollinated. Even though, for example tomato, self-pollinate, they need the help of the insects to create vibrations within the flowers that will effectively loosen the pollen. Paddy is mostly self-pollinating using just gentle wind as the pollinating agent.

24. The agents that are helping in pollination are called __________

Transmitter
Carrier
Pollinator
Contaminator

Explanation

The agents that are helping in pollination are called pollinators.

25. Which among the following statement is correct

The process by which human transfer the pollen grains from male flower to the female flower artificially is called artificial pollination. However, in nature there are many ways in which pollen grains reach the stigma of the flower and is called as natural pollination.
When you shake stamens, pollen grains fallout. Thus, when a wind shakes the flower or when a butterfly agitates the flower, pollen grains could fall onto the stigma of same flower. Some plants that have both the male and female parts within a single flower (unisexual) pollinate by this means. This is called as Point-pollination.
Only 1
Only 2
Both 1 and 2
None

Explanation

When you shake stamens, pollen grains fallout. Thus, when a wind shakes the flower or when a butterfly agitates the flower, pollen grains could fall onto the stigma of same flower. Some plants that have both the male and female parts within a single flower (bisexual) pollinate by this means. This is called as Self-pollination.

26. In flower after pollination, male gamete fuses with the female gamete to form zygote. This process is known as _________

Construction
Sterilization
Fertilization
Stimulation

Explanation

During the germination a tube develops from the pollen grain that carries male gametes that ultimately reaches female gamete inside the ovary through the style. Male gamete fuses with the female gamete to form zygote. This process is known as fertilization.

27. What is the small rounded structure present inside the ovary is called _________

Stamen
Pollen
Ovule
Pedicel

Explanation

Inside the ovary, small rounded structures, ovules are present. In these ovules, female gamete is present.

28. Which among the following statement about the fruits is incorrect

A green part above fruits of brinjal and lady’s finger are petals of a flower. In some, after fertilization, petals will not fall from fruit and remain or persist with fruit. In pea, fruit is fleshy and forms a covering pouch for many seeds.
Custard apple is made up of many fruits, aggregated together. Each fruit part is thin, membranous with some granule like, which is edible. In mango outer skin and middle pulpy are edible and sweet. Inner most is with single seed.
In all above fruits, ovary, a lower most swollen part of pistil develops into a fleshy fruit. Ovules present inside the ovary gets transformed into a seed. These are change take place in flower after fertilization.
Both 1 and 2
Both 1 and 3
Both 2 and 3
All 1, 2 and 3

Explanation

A green part above fruits of brinjal and lady’s finger are sepals of a flower. In some, after fertilization, sepal will not fall from fruit and remain or persist with fruit. In pea, fruit is not fleshy, but forms a covering pouch for many seeds.

29. Which among the following is not the post fertilization changes?

Calyx sometimes persists with fruit
Androecium sticks to seeds
Style and stigma fall of
Ovules present inside the ovary develops into seeds

Explanation

The post fertilization changes and are: 1. Calyx sometimes persist with fruit 2. Petals wither / fall off 3. Androecium fall off. 4. Pistil remain and develops into a fruit. 5. Style and stigma fall off 6. Ovary enlarges to store food materials and develops into a fruit. 7. Ovules present inside the ovary develops into seeds.

30. The world’s largest and heaviest seed is __________

Double melon
Double coconut
Double paddy
Double corn

Explanation

The world’s largest and heaviest seed is the double coconut. The seed looks like two coconut fused together. It only grows in two islands of the Seychelles. A single seed may be 12 inches long, nearly 3 feet in circumference and weighs about 18 kg.

31. Which have the smallest seeds in the plant kingdom?

Vanda
Lily
Hibiscus
Orchid

Explanation

Orchids have the smallest seeds in the plant kingdom. 35 million seeds may weight only about 25 grams.

32. The production of new plants without the involvement of pollination and fertilization is knows ____________

Unisexual reproduction
Bisexual reproduction
Asexual reproduction
All the above

Explanation

Earlier we saw that plants reproduce not only from seeds but by other processes as well. The production of new plants without the involvement of pollination and fertilization is knows as asexual reproduction.

33. Which among the following is not the types of asexual reproduction?

Budding
Fragmentation
Spore formation
Fermentation

Explanation

The types of asexual reproduction are 1. Vegetative Propagation, 2. Budding, 3. Fragmentation and 4. Spore formation.

34. The soft nature in bread and cakes are due to what reason?

Bacteria
Yeast
Mold
None of the above

Explanation

When we go to a bakery, we see so many types of cakes and breads. These are very soft in nature. This is due to the presence of Yeast.

35. Single yeast undergoes asymmetric division and produces a small protuberance which gradually grows and detaches from the parent cell. This process is called _________

Spore formation
Fragmentation
Budding
Vegetative propagation

Explanation

Single yeast undergoes asymmetric division. It produces a small protuberance which gradually grows and detaches from the parent cell. This process is called budding.

36. Which is a filamentous alga, when it matures, the filament divides into pieces and each fragment or piece of a filament will grow into a new filament or individual?

Spirogyra
Chlamydiae
Firmicutes
Eumycota

Explanation

In a pond we see so many algae. Spirogyra is a filamentous alga, when it matures, the filament divides into pieces. Each fragment or piece of a filament will grow into a new filament or individual. Likewise, Spirogyra produces so many young ones and this process is known as fragmentation.

37. Which among the following is not Vegetative Propagating plant?

Potato
Corn
Sugarcane
Yam

Explanation

In potato, shoot arise from eyes. Sugarcane, yam also grown like this. Vegetative parts of the plants such as root, stem and leaves can help to propagate the plant. Corn does not undergo vegetative propagation.

38. Which among the following is not non-flowering plant?

Moss
Ferns
Algae
Water meal

Explanation

Scarcity of water, high temperature, nutrient deficiency in soil etc., are unfavourable conditions. During these conditions non-flowering plants like Algae, Fungi, Moss and Ferns produces spores. They germinate into a new plant when favourable conditions are returns.

39. Carrot comes under which types of roots?

Fibrous roots
Taproots
Parasite roots
Adventitious roots

Explanation

Look at the part we usually consume as ‘carrot vegetable’. However, it is not an unripe fruit, but the tap root of the carrot plant. We can see that the tap root of the carrot is swollen. In the case of the carrot plant, the tap root has a different characteristic than the usual pants.

40. Which among the following statement is correct

Normally, each plant organ, originally evolved to meet certain needs of the plant. For example, roots evolved primarily to anchor the plant and also absorb water and mineral nutrients from soil. Leaves were adapted to optimize photosynthesis. Stems evolved to reach out to sunlight and also served to conduct water from roots to leaves.
However, in certain plant species, specific parts have evolved further in unusual and surprising ways to meet certain other specific needs, in some plants root, stem, and leaves change their shape and structure to perform special functions like storage of food, mechanical support, protection and other vital functions. This is known as modification.
What appear as the ‘leaf’ of a cacti are actually their flower and what appear as ‘spine’ on them are actually stem. Its stems are modified into spines, an adaptation to reduce transpiration. Photosynthesis is performed by the stem part of the plant.
Both 1 and 2
Both 1 and 3
Both 2 and 3
All 1, 2 and 3

Explanation

What appear as the ‘leaf’ of a cacti are actually their stem and what appear as ‘spine’ on them are actually leaf. Its leaves are modified into spines, an adaptation to reduce transpiration. Photosynthesis is performed by the stem part of the plant.

41. Which among the following is not the plant that stores food in roots?

Radish
Turnip
Beet root
None of the above

Explanation

Look at a radish, turnip, beet root, and carrot. They all grow under the soil. As soon as you pluck it from the ground if you wash them gently, you will notice small roots dangling from their surface. All these vegetables are in fact roots of the plant. Instead of thin slender roots, in case of such plants, the roots have become a place to store the food produced by them.

42. Which among the following is the example of spindle shaped root?

Carrot
Radish
Beet root
All the above

Explanation

One can notice that the tap root of radish is in the shape of spindle, swollen in the middle and tapering at both ends. Such type of modified roots is called spindle shaped root.

43. Which among the following is not Top shaped root?

Carrot
Turnip
Beetroot
None of the above

Explanation

At times, like in the case of turnip, and beet root the tap root can acquire a shape of top, that is spherical at the base and tapering shortly towards the apex. They are called as Top shaped root.

44. Carrot is an example of which type of roots?

Spiral shaped root
Conical shaped root
Marrow shaped root
Double tapped root

Explanation

In case of carrot, the shape is conical, broad at the apex and tapering gradually towards the base and such modified roots are called Conical shaped root.

45. Which among the following plant has mechanic support root?

Banyan
Papaya
Neem
All the above

Explanation

Look at a banyan tree. It seems to have many trunks supporting it. However, many of them are actually roots. As the banyan tree is large and huge, it needs support not to tilt and fall down. Many plants require such additional support. Such plants develop roots on their aerial parts to provide mechanical support. These roots grow downward and act as supportive organs.

46. Which among the following is not the modified root for support?

Prop roots
Fixed roots
Stilt roots
Climbing roots

Explanation

There are three types of modified roots for support. i. Prop roots, ii. Stilt roots and iii. Climbing roots.

47. A root growing from a location other than the underground, such as from a stem or leaf is called as __________

Fibrous roots
Taproots
Parasite roots
Adventitious roots

Explanation

A root growing from a location other than the underground, such as from a stem or leaf is called as adventitious root.

48. Banyan tree is an example of which among the following root?

Climbing root
Prop root
Stilt root
Sucking root

Explanation

Prop roots: Roots are modified to provide mechanical support as seen in Banyan tree. These roots grow vertically from horizontal branches of a tree.

49. Which among the following is not the example of stilt roots which gives additional support?

Sugar cane
Black pepper
Maize
None of the above

Explanation

In sugar cane, and maize adventitious roots arise from the nodes in cluster at the base of the stem. These roots are called stilt roots which gives additional support.

50. Which among the following is not the example of climbing roots?

Betel
Black pepper
Avicennia
None of the above

Explanation

Climbing roots: In betel and black pepper, nodes or inter modes bear roots which help in climbing.

51. Which among the following is not the type of Modification of Roots?

Roots for storage
Mechanical support
Gaseous exchange
Aerial modification

Explanation

The four types of modification of roots are 1. Roots for storage, 2. Mechanical Support, 3. Gaseous Exchange and 4. Roots for other vital function.

52. Cascuta a parasite plant is example of which among the following roots types?

Pneumatophores
Haustoria
Phylloclade
Rhizome

Explanation

Roots may also perform special function. Haustoria or Sucking roots, are one such example. Cuscuta a parasite plant, climb the trees and other vegetation and use the haustoria roots to penetrate the tissue of the host plant and suck nutrients from them. They are usually found in parasitic plants that depend on the host plants for nutrients.

53. Which is an epiphytic plant, which grows on trees and the velamen tissue present in the epiphytic root, absorbs moisture, to perform photosynthesis?

Plumbago
Ipomoea
Iresene
Vanda

Explanation

Vanda is an epiphytic plant, which grows on trees. The velamen tissue present in the epiphytic root, absorbs moisture, to perform photosynthesis.

54. Which is a tree which grows in mangroves or swamps that have roots which are seen above the ground for the purpose of gaseous exchange?

Mahogany
Rhododendron
Cedar
Avicennia

Explanation

Avicennia is a tree which grows in mangroves or swamps. They have roots which are seen above the ground for the purpose of gaseous exchange. These roots are erect, peg like structures with numerous pores through which air circulates. These roots are called breathing roots, or pneumatophores.

55. Which among the following is not the stem?

Ginger
Onion bulb
Potato
None of the above

Explanation

Can you guess what is common between ginger, onion bulb, potatoes. All three are stems. Some plants have their stems modified for storing food and for vegetative propagation. Modified stem may be aerial, subaerial or underground stems.

56. Which among the following is not the Sub – aerial Modifications stem types?

Phylloclade
Runner
Stolon
Sucker

Explanation

Stem of some plants remains sub – aerial which grow horizontally on the surface of the soil for the purpose of reproduction. There are four types. 1. Runner, 2. Stolon, 3. Sucker and 4. Offset.

57. Which among the following is the example of runner stem?

Wild strawberry
Centella
Chrysanthemum
Eichhornia

Explanation

Runner: The stem grows laterally on the surface of the soil, breaks up to produce roots where it touches the ground to give rise to new plants. E.g: Centella (Vallarai).

58. Which is a short and thick branch that arises from the axial part of a leaf and has thick internodes and produces a tuft of leaves and cluster of small roots below?

Runner
Stolon
Sucker
Offset

Explanation

An offset is a short and thick branch that arises from the axial part of a leaf. It has thick internodes. It produces a tuft of leaves and cluster of small roots below. E.g: Eichhornia.

59. Which among the following is the example of stolon?

Colocasia
Wild strawberry
Chrysanthemum
Potato

Explanation

Sucker is a short and weak lateral branch that grows diagonally upwards and directly gives rise to a new shoot. E.g: Chrysanthemum.

60. Cactus is an example of which among the following stem modification?

Stolon
Phylloclade
Rhizome
Bulb

Explanation

Phylloclade: In dry climate, conserving water is a challenge. Water evaporates from the surface. If the surface area is larger, evaporation would be more; and if the surface area is smaller, the evaporation will be less. Plants with many leaves have more surface area. Cactus hence has a thick stem which does most of the food production through photosynthesis and leaves are reduced to small spines with less surface area.

61. Which is a slender branch of the stem that grows upwards to some distance and then bends towards the ground and upon touching the ground, it gives rise to a new plant?

Stolon
Rhizome
Bulb
Corm

Explanation

Stolon is a slender branch of the stem that grows upwards to some distance and then bends towards the ground. Upon touching the ground, it gives rise to a new plant. E.g: Wild strawberry.

62. Which among the following is not the underground stem types?

Corm
Spines
Tuber
Bulb

Explanation

In aerial and sub aerial modifications, stem has indefinite growth. In underground modified stem, whole stem is buried under the ground and it has definite growth. Usually stem grows above the ground, but there are some stems that grow under the ground to store food. These underground stems swell and become thick. There are four types of underground stems: 1. Rhizome; 2. Corm; 3. Tuber; 4. Bulb.

63. Which is an enlarged, spherical underground stem that stores food and has many dormant buds on its surface known as “Eyes”?

Rhizome
Corm
Tuber
Bulb

Explanation

Tuber is an enlarged, spherical underground stem that stores food. It has many dormant buds on its surface known as “Eyes”. If we plant a part of tuber with the bud, it grows into a new plant.

64. Which among the following is the example of tuber stem?

Potato
Ginger
Turmeric
Garlic

Explanation

Potato is an example of Tuber.

65. Which is an underground thick stem with nodes and internodes with scale leaves at the node and grows horizontally and has an irregular shape?

Rhizome
Corm
Tuber
Bulb

Explanation

Rhizome is an underground thick stem with nodes and internodes with scale leaves at the node. It grows horizontally and has an irregular shape. Rhizome have buds. If give rise to new stem and leaves.

66. Which is underground stem round in shape and flat at the top and bottom. It is a condensed form of rhizome and bears one or more buds in the axils of scale leaves?

Rhizome
Corm
Tuber
Bulb

Explanation

Corm is an underground stem which is round in shape and flat at the top and bottom. It is a condensed form of rhizome and bears one or more buds in the axils of scale leaves. Daughter plants arise from their buds.

67. Which among the following is not the example of Rhizome?

Ginger
Onion
Turmeric
None of the above

Explanation

Ginger and Turmeric are example of Rhizome.

68. Which among the following is the example of Corm?

Garlic
Onion
Colocasia
All the above

Explanation

Colocasia is an example of corm.

69. Which is a condensed stem which is disc like and stores food in the fleshy leaves?

Rhizome
Corm
Tuber
Bulb

Explanation

Bulb is a condensed stem which is disc like and stores food in the fleshy leaves.

70. The bulb has how many types of leaf?

Two
Three
Four
Six

Explanation

The bulb has two types of leaves. 1. Fleshy Leaves 2. Scaly Leaves. The upper part of the stem has a terminal bud and it is covered by many scaly leaves. The inner fleshy leaves store food as seen in Garlic and Onion.

71. Which among the following is not the modifications of leaf?

Spines
Tendrils
Traps
Moles

Explanation

Plants have changed themselves to adapt to the environment they grow. One of them is the modification of leaves. Leaves of several plants get modified into different form based on the purpose and environment. They are i. Spines, ii. Tendrils, iii. Phyllode and iv. Traps.

72. Which among the following is the example of traps leaf?

Opuntia
Pea
Nepenthes
Acacia

Explanation

Nepenthes is the example of Traps.

73. Plants like Nepenthes have which deficiency that makes them adopt to be traps?

Oxygen
Hydrogen
Carbon
Nitrogen

Explanation

Plants that grow in nitrogen deficient places adapt themselves well to get it. In Nepenthes, the leaves are modified into a flask like structure, which is used to attract insects and other tiny animals. The inner wall of the leaf secretes digestive enzymes that help to digest the insects and extract the nitrogen needed for the plant. Eg: Nepenthes.

74. Which among the following statement is incorrect

Phyllode: In Acacia auriculiformis, petioles expand to form leaf like structure. They carry out the function of leaf (Photosynthesis).
Tendrils: In climbers, the leaf of plant would be modified into elongated structure to help the plants climb efficiently. 1. Gloriosa superba – Leaf tips are modified into tendrils 2. Pisum sativum (pea) –Terminal leaflets are modified into tendrils.
Only 1
Only 2
Both 1 and 2
None

75. Which among the following is the example of spines (Modifications of Leaf)?

Perennial
Opuntia
Spiraea
Clethra

Explanation

Leaves are reduced to spines, and the stem is modified into green succulent part to perform photosynthesis. Eg : Opuntia

7th Science Lesson 6 Questions in English

6] Health and Hygiene

1. Which refers to the good habits and their practices which is followed to prevent diseases, maintain good health, especially through cleanliness, consumption of safe drinking water and proper disposal of sewage?

Hospitality
Hygiene
Contamination
Psychedelic

Explanation

Hygiene refers to the good habits and their practices which is followed to prevent diseases, maintain good health, especially through cleanliness, consumption of safe drinking water and proper disposal of sewage. It refers to all those activities that are done for improving and maintaining good health and sound mind.

2. Which among the following statement is correct

Health is the best wealth. If you have good health, you will have a sound mind and you will gain good knowledge and wealth also. To maintain good health, you should follow good hygiene, eat nutritious food, do exercise, take rest and have a sound sleep. It is also referring to a state of a sound mind and body free from any sickness or ailment, stress and problems.
Cleanliness refers to the maintenance of personal and environmental hygiene. In simple words, it refers to the state of being clean which is essential for good health. To protect us from diseases it is essential to maintain good health by taking regular bath, cleaning the clothes and surroundings and also avoiding unhygienic food consumption.
Only 1
Only 2
Both 1 and 2
None

3. Which among the following does not cause colds and flu?

Bacteria
Fungus
Virus
Both Bacteria and Fungus

Explanation

Colds and the flu are common communicable diseases. It is caused not only by bacteria but also by virus.

4. Which among the following is not the symptoms of colds and flu?

Cough
Fever
Pain in joints
None of the above

Explanation

When you have cold and flu, you may also have running nose, cough, sore throat, and sometimes fever or pain in the joints. For some, this condition may also lead to mild diarrhoea.

5. Which is defined as “the branch of health which is concerned with the individual’s adjustment to the physiological needs of the body and mind for the attainment of the maximum level of health, it also refers to the cleaning and grooming of the body?

Community hygiene
Personal hygiene
Collar hygiene
All the above

Explanation

Personal hygiene is defined as “the branch of health which is concerned with the individual’s adjustment to the physiological needs of the body and mind for the attainment of the maximum level of health, it also refers to the cleaning and grooming of the body.

6. Which among the following statement is correct

Secretions oozing out from the nose may contains virus not bacteria. When the patient touches the nose and some other object or someone else the virus is transferred. When the patient sneezes or coughs the virus comes out with the droplets and become airborne
Hence it is a good practice for the patient with cold and flu to use a handkerchief to blow the noses and also wash the hands often to ensure that they do not accidentally spread the virus to others.
Only 1
Only 2
Both 1 and 2
None

Explanation

Secretions oozing out from the nose may contains the bacteria or virus. When the patient touch the nose and some other object or someone else the virus is transferred. When the patient sneezes or coughs the virus comes out with the droplets and become airborne.

7. Which among the following is incorrect about adoption measures for community hygiene?

The surroundings should be kept clean.
Drains should be covered properly.
The domestic wastes should be segregated and properly disposed of safely in separate dust bins provided by the Government (Green and Blue).
Used water from houses should be let out into open drains or open areas.

Explanation

Used water from houses should not be let out into open drains or open areas.

8. Which among the following mosquito spread Dengue?

Psorophora
Culex
Aedes
Mansonia

Explanation

Dengue is spread by mosquitoes of Aedes aegypti caused by DEN-1, 2 viruses belonging to the type- flavivirus. It decreases counting of the blood platelets of human blood and it has a maximum flight range of 50–100 meters in and around the places.

9. Which among the following is the core systems that should be in synchronization and functioning well?

Digestive system
Circulatory system
Muscular system
All the above

Explanation

The human body systems work well with proper maintenance and guidance. For smooth functioning, all the parts of the body should work in unison. The digestive system, circulatory and muscular system is the core systems that should be in synchronization and functioning well. So keep them well by proper care.

10. The act of chewing and tasting is called ____

Fibrillation
Mastication
Articulation
Dissipation

Explanation

Good oral hygiene implies sound teeth and healthy gums with healthy surrounding tissues. The physical act of chewing food promotes saliva and gastric secretions which helps digestion. The act of chewing and tasting is called ‘mastication’. It gives pleasure and emotional satisfaction of eating food.

11. Which among the following statement is correct

Teeth is essential for good appearance and clear speech also. When you brush two times a day, it will prevent the formation of tartar and plaque on your teeth and gums.
When you Floss, it will remove food particles, plaque which build up between your teeth but it will not remove bacteria. When you start flossing, your gums may bleed a little bit, but after few days that will be stopped.
Only 1
Only 2
Both 1 and 2
None

Explanation

When you Floss, it will remove food particles, plaque, and bacteria which build up between your teeth. When you start flossing, your gums may bleed a little bit, but after few days that will be stopped. It should be started only with proper medical guidance.

12. Which among the following is the causes of bleeding gums?

Bacteria in plaque
Vitamin E deficiency
Vitamin C deficiency
Vitamin B1 deficiency

Explanation

Bleeding gums is caused by Vitamin C deficiency. Remedial measures are eating citrus fruits.

13. Which among the following is the cause of Tooth decay?

Bacteria in plaque
Vitamin E deficiency
Tobacco chewing
Vitamin B1 deficiency

Explanation

Tooth decay is caused by Bacteria in plaque. Bacteria produce acids. Brushing and flossing the teeth can prevent decay are remedial measures.

14. Which among the following is the cause of Periodontitis?

Bacteria in plaque
Vitamin E deficiency
Tobacco chewing
Vitamin B1 deficiency

Explanation

Periodontitis is caused by Tobacco chewing. It is severe form of gum disease ruin the bones, gums, and other tissues. Remedies for Periodontitis is chewing type of tobacco should be avoided. Eat a well-balanced diet.

15. Which among the following are considered as “windows to the world”?

Ears
Eyes
Nose
Mouth

Explanation

Eyes are an important organ of our body. Th ey are considered as “windows to the world”.

16. How many percentages of what we perceive comes through the sense of sight?

50%
70%
80%
90%

Explanation

Eyesight is the most important sense. 80% of what we perceive comes through the sense of sight. The protection of the eyes, can reduce the odds of blindness and vision loss. we protection of our eye from the diseases, surroundings, climate condition.

17. Which among the following statement is correct

The condition of the hair reflects to some extent the nutritional status and general health of the body. Thin, sparse hair and the loss of hair indicates a poor nutritional status. The deficiencies in diet, physical and mental illness of various kinds may also lead to premature greying of hair.
The hair follicles from which the hair grows produce oil which keeps the hair smooth. The sweat and the dead skin cells come off the scalp. The oil, sweat and dead cells all add together and can make the hair greasy and look dirty unless it is washed regularly. The regular hair wash and massage of the scalp will remove the dead skin cells, excess oil and dust.
Only 1
Only 2
Both 1 and 2
None

18. Which among the following is the causative agents of Conjunctivitis?

Lack of vitamin C
Bacteria
Virus
Both bacteria and virus

Explanation

Conjunctivitis (Pink eye) is caused by a virus and bacteria. One or both eyes can be affected. Highly contagious; can be spread by contamination and sneezing. Antibiotic eye drops or ointments, home remedy.

19. Which among the following is the causative agents of Night blindness?

Lack of vitamin C
Virus
Lack of vitamin A
Genetics Condition

Explanation

Night Blindness is caused by a lack of vitamin A, a disorder of the cells in your retina. It makes hard to see well at night or in poor light. Eat foods rich in antioxidant, vitamins and minerals as remedies.

20. Which among the following is the causative agents for colour blindness?

Lack of vitamin C
Virus
Lack of vitamin D
Genetics Condition

Explanation

Colour blindness is caused by genetic condition. Difficulty distinguishing between colours and Inability to see shades or tones of the same colour. There is no known cure for colour blindness. Contact lenses and glasses with filters.

21. Which is the functional or physical change from a normal state that affects the health of a person by causing disability or discomfort?

Diet
Hygiene
Disease
All the above

Explanation

A disease is the functional or physical change from a normal state that affects the health of a person by causing disability or discomfort.

22. Which among the following is not the reason that leads to the development of disease in an individual?

Lack of balanced diet
Poor lifestyle and unhealthy habits
Malfunctioning of one or more body parts or organs
None of the above

Explanation

The following are reasons that could leads to the development of disease in an individual. 1. Infection caused by disease-causing microbes, 2. Lack of balanced diet, 3. Poor lifestyle and unhealthy habits and 4. Malfunctioning of one or more body parts or organs.

23. The prevention and treatment of sickness can be considered in how many groups?

Two
Three
Four
Five

Explanation

The prevention and treatment of sickness can be considered in two groups for their better understanding. They are, communicable and non-communicable disease.

24. Which among the following is not the communicable disease?

Anaemia
Cholera
Hepatitis
Chickenpox

Explanation

Communicable diseases are those that spread from one person to another. Healthy persons must be protected from people with communicable diseases. Diseases spread through contaminated air, water, food or vectors (insects and other animals). Anaemia is a non-communicable disease.

25. Which among the following is not the disease caused by bacteria?

Tuberculosis
Cholera
Hepatitis
Typhoid

Explanation

The communicable disease (like tuberculosis, Cholera and Typhoid), which are caused by microbes and spread through air, water and some other organisms also.

26. Tuberculosis is caused by which bacteria?

Mycobacterium tuberculae
Vibrio tuberculae
Salmonella tuberculae
Chlamydiae tuberculae

Explanation

Tuberculosis is caused by Mycobacterium tuberculae and spreads from one person to another person through air by spitting and prolonged contact with sharing materials of the patient.

27. Which among the following is not the symptoms of Tuberculosis?

Fever
Blood in urine
Weight loss
Blood spitting

Explanation

The symptoms of Tuberculosis are fever, weight loss, chronic cough, bloody spitting and difficulty in breathing.

28. Which among the following is the vaccine used against Tuberculosis?

ADC vaccine
PS vaccine
BCG vaccine
TED vaccine

Explanation

BCG vaccine is used against tuberculosis. Giving special attention to the patient and Regular medication like DOT are treatment.

29. Which among the following cause cholera?

Nitrospirae cholera
Vibrio cholera
Varicella cholera
Salmonella cholera

Explanation

Cholera is caused by Vibrio cholera and spread through the consumption contaminated food or water.

30. Which among the following is not the symptoms of Cholera?

Vomiting
Blood spitting
Diarrhoea
Cramps in legs

Explanation

The symptoms of Cholera are Vomiting, severe diarrhoea and cramps in legs.

31. Which among the following is not prevention and treatment for cholera?

Good hygienic practices like, washing hands before eating
Drinking ice water
Getting Vaccination against cholera
Avoid eating uncovered food from street vendors.

Explanation

Prevention and treatment 1. Good hygienic practices like, washing hands before eating. 2. Avoid eating uncovered food from street vendors, 3. Drinking boiled water and 4. Getting Vaccination against cholera.

32. Typhoid is caused by _________

Salmonella typhi
Nitrospirae typhi
Varicella typhi
Chloroflexi typhi

Explanation

Typhoid is caused by Salmonella typhi and spreads by contaminated food and water.

33. Which among the following is not the symptom of Typhoid?

Anorexia
Headache
Yellow eye
Rashes on abdomen

Explanation

The symptoms are Anorexia, headache, rashes on abdomen, dysentery and high fever up to 104⁰F. The prevention and treatment are Drinking boiled clean water, Proper disposal of sewage and Vaccination.

34. Which among the following is not the viral disease?

Hepatitis
Chickenpox
Rabies
Leukoderma

Explanation

Viral diseases are extremely widespread infections caused by many types of viruses. In this lesson you will learn about some disease caused by viruses like, Hepatitis, Chickenpox and Rabies.

35. Which among the following is not the symptoms of Hepatitis?

Anorexia
Vomiting
Yellow eye
Rashes on whole body

Explanation

Hepatitis is one of the most dangerous and fatal diseases caused by Hepatitis virus A, B, C, D, E. Its mode of transmission is Contaminated water, sharing of needles and blood transfusion. The symptoms of hepatitis are loss of appetite (Anorexia), vomiting, eyes and urine in yellow colour.

36. Chickenpox (chicken pox), also known as ________

Plague
Chlamydiae
Varicella
Moringa

Explanation

Chickenpox (chicken pox), also known as varicella, is a highly contagious infection caused by the varicella zoster virus. This disease spreads through air and contact with an infected person.

37. Which among the following is not the symptoms of chickenpox?

Urine in yellow colour
Rashes on whole body
Fever
Headache

Explanation

Chickenpox symptoms is appearance of rashes on the whole body, fever, headache and tiredness. The chickenpox (varicella) vaccine is the best way to prevent chickenpox. Special attention should be given to the infected persons.

38. Which among the following infected animal bite cause Rabies?

Dog
Rabbit
Cat
All the above

Explanation

Rabies is a fatal disease. Which is transmitted by the bite of the infected dog, rabbit, monkey, cat etc. The virus present in the saliva of dog enters the brain via neurons.

39. Which among the following phobia is caused by Rabies?

Acrophobia
Hydrophobia
Claustrophobia
All the above

Explanation

The symptoms of rabies are hydrophobia (extreme fear for water), fever for 2 – 12 weeks and exaggerations in behaviour.

40. Which among the following statement is incorrect

In early stages rabies is very difficult to detect. Fatality can be prevented by timely vaccination before the onset of symptoms.
After an animal is bitten it usually takes twelve to forty-eight hours to shows any symptoms and it may take as long as one week also.
Only 1
Only 2
Both 1 and 2
None

Explanation

After an animal is bitten it usually takes two to twelve weeks to shows any symptoms and it may take as long as two years also.

41. Which among the following factor cause Non-communicable diseases?

Germs
Bacteria
Microbic living organism
None of the above

Explanation

Non-Communicable diseases do not spread from person to person. They are caused by other factors. Therefore, it is important to know which sickness are communicable and which are not. They are never caused by germs, bacteria, or other living organisms that infect the body. Antibiotics, or medicines that fight against germs do not help to cure noncommunicable diseases.

42. Which among the following is not the Problems caused by wearing out of body parts?

Cataract
Migraine headache
Rheumatism
Anaemia

Explanation

Problems caused by wearing out of body parts are Rheumatism, heart attack, epileptic seizures, stroke, migraine headache. Cataract and cancer.

43. Which among the following is not the Problems caused by a lack of trace elements in the body?

Anaemia
Pellagra
Asthma
None of the above

Explanation

Problems caused by a lack of trace elements in the body are Anemia, pellagra, night blindness and xerophthalmia, goitre and hypothyroidism.

44. Which among the following statement is correct regarding rabies?

Virus enters via animal bite. Virus replicates in muscle at site of bite. Virus infects nerve in peripheral nervous system. Moves by retrograde transport. Virus replicates in dorsal root ganglion and travels up spinal cord to brain.
Brain infected and Virus travels from brain via nerves to other tissues such as eye, kidneys, salivary glands.
Only 1
Only 2
Both 1 and 2
None

45. Which among the following is not the Problems caused by external harmful agents entering the body?

Allergies
Poisons
Stomach ulcer
None of the above

Explanation

Problems caused by external harmful agents entering the body are Allergies, asthma, poisons, snakebite, cough from smoking, stomach ulcer, alcoholism. Nutritious food is needed for a person to grow well, work hard, and stay healthy. Many common sicknesses are caused by malnutrition.

46. Which is a non – communicable diseases caused by partial or total loss of pigmentation in the skin?

Osteoporosis
Leucoderma
Alzheimers
Trauma

Explanation

Leucoderma is a non – communicable diseases caused by partial or total loss of pigmentation in the skin. (melanin pigment). This condition affects any age, gender and ethnicity. There is no cure. It does not spread by touching, sharing food and sitting together.

47. Which is caused by eating food with less iron content and can also caused due to feeding some other foods instead of breast milk?

Anaemia
Asthma
Pellagra
Goitre

Explanation

Anaemia is caused by eating food with less iron content and can also cause due to feeding some other foods instead of breast milk.

48. Severe anaemia in children does not leads to which among the following?

Hookworm infection
Chronic diarrhoea
Liver fever
Dysentery

Explanation

Severe anaemia in children may leads to hookworm infection, chronic diarrhoea and dysentery. In recent day school going children, especially the girls are affected by anaemia. The Government of Tamil Nadu provides weekly iron folic tablets to all the girls in the schools of all areas.

49. Which among the following statement is not signs of anaemia?

Pale or transparent skin, the inner surface of eye lids is pale
In severe cases, face and feet may be swollen
The heartbeat is rapid and with shortness of breath
All the above

Explanation

The signs of anaemia are: 1. Pale or transparent skin, the inner surface of eye lids are pale, white fingernails, pale gums, weakness and fatigue,2. In severe cases, face and feet may be swollen, the heartbeat is rapid and with shortness of breath,3. Children and women who eats mud are usually anaemic.

50. Which among the following is not the iron containing food source?

Moringa leaves
Dates
Carrot
Beans

Explanation

Food – Moringa leaves, Dates, Liver (Sheep and Chicken), Green, green leafy vegetables like beans, peas, lentils and Greed banana.

51. Which among the following pills does not contain iron source?

Cod liver oil table
Ferrous sulphate
Vicodin
None of the above

Explanation

Pills that contain iron are Cod liver oil tablet, Ferrous sulphate. As a general rule, iron supplements should be given orally, not to be injected, because it leads to dangerous.

52. The first aid is given for which among the following purpose?

To save the life
To prevent further bleeding and determine the condition of the patient
To relieve the pain
All the above

Explanation

First aid is the immediate treatment given to the victim of trauma or sudden illness before medical help is made available. The first aid is 1. To save the life 2. To prevent further bleeding and determine the condition of the patient 3. To relieve the pain and 4. To provide a medical care available at the earliest.

53. The tissue damage caused by heat, chemical, electricity, sunlight or nuclear radiation is known _______

Cuts
Burns
Scratches
All the above

Explanation

The tissue damage caused by heat, chemical, electricity, sunlight or nuclear radiation is known as Burns. Mostly burns are caused by scalds, building fires, flammable liquid and gases.

54. There are how many types of burns, according to degree of burning?

Two
Three
Five
Six

Explanation

There are three types of burns, according to degree of burning.

55. The outer layer of the skin is called as ________

Epidermis
Pro dermis
Dermis
Cal dermis

Explanation

First-degree burns affect only the outer layer (called the epidermis) of the skin.

56. The layer beneath the epidermis is called as __________

Pro dermis
Dermis
Cal dermis
Hypodermis

Explanation

Second-degree burns damage the epidermis and the layer beneath it (called the dermis). Third-degree burns involve damage or complete destruction of the skin to its full depth and damage to underlying tissues also. People who experience such burns often require skin grafting.

57. Which among the following statement is correct

In case of minor burns, the affected area should not be washed with cold water but an antiseptic cream can be applied. In case of severe burns, where deeper layers of tissues get destroyed and blisters appear, use of water is necessary. The burnt area should be covered with a clean non- sticking cloth or bandages. Larger burns need immediate medical attention.
Cuts and scratches are areas of damage on the surface of the skin. A cut is a line of damage that can go through the skin and into the muscle tissues below, whereas a scratch is surface damage that does not penetrate the lower tissues. Cuts and scratches may bleed or turn red, become infected and leave scars.
For minor cuts, the affected area should be washed with cold running water and cleaned with an antiseptic liquid. Then apply an antiseptic cream on the wound and sterilized bandage should be tied to prevent infection. If the cut is deep, a clean cotton pad should be placed on the cut and pressed, and the injured person should be taken to a doctor immediately.
Both 1 and 2
Both 1 and 3
Both 2 and 3
All 1, 2 and 3

Explanation

In case of minor burns, the affected area should be washed with cold water and an antiseptic cream should be applied. In case of severe burns, where deeper layers of tissues get destroyed and blisters appear, use of water should be avoided. The burnt area should be covered with a clean non- sticking cloth or bandages. Larger burns need immediate medical attention.

58. Which among the following is known as queen of medicines?

Cyclosporine
Penicillin
Paracetamol
Amoxicillin

Explanation

Penicillin is known as queen of medicine.

59. Who among the following discovered penicillin?

Alexander Fleming
Howard Florey
Robert Koch
Louis Pasteur

Explanation

Alexander Fleming discovered Penicillin. The world’s first antibiotic penicillin was discovered in 1928.

60. Penicillin cured which among the following?

Pneumonia
Diphtheria
Infected wounds
All the above

Explanation

Penicillin cured Pneumonia, Diphtheria and infected wounds. Alexander saved the life of many soldiers and prevented the communicable disease by using penicillin. later, penicillin is used as the universal antibiotic. The discovery of Alexander is known as the ‘Queen of Medicines’ as the provided great benefits in the field of medicine.

61. Where Alexander Fleming did his schooling and college?

America
London
India
German

Explanation

Alexander Fleming did his school education at St. Mary’s school in London. As he was very much interested in studying medicine at the age of 20, he joined medical course at St. Mary’s Medical College and Hospital with the help of his uncle.

62. In which war Alexander Fleming was appointed the Chairman of the Medical Board for military soldiers?

First world war
Second world war
Ottoman war
Napoleonic war

Explanation

In the first world war, soldiers were wounded heavily and hence many were infected with contagious diseases. He was appointed the Chairman of the Medical Board for military soldiers.

63. Which among the following micro-organism produced Penicillin?

Bacteria
Fungus
Virus
Archaea

Explanation

Penicillin produced by the fungus Penicillium notatum destroyed the bacteria.

7th Science Lesson 7 Questions in English

7] Heat and Temperature

1. Assertion(A): You shiver when it is cold outside and sweat when it is hot outside

Reason (R): Temperature is involved in many aspects of our daily lives, including our own bodies and health

Both (A) and (R) are correct, but (R) does not explain (A)
Both (A) and (R) are wrong
Both (A) and (R) are correct and (R) explains (A)
(A) is Correct and (R) is wrong

Explanation

You shiver when it is cold outside and sweat when it is hot outside, but how can you measure those weather temperatures? Temperature is involved in many aspects of our daily lives, including our own bodies and health; the weather; and how hot the stove must be in order to cook food.

2. The measurement of warmness or coldness of a substance is known as its_____

Heat
Kinetic energy
Potential energy
Temperature

Explanation

The measurement of warmness or coldness of a substance is known as its temperature. Temperature is related to how fast the atoms within a substance are moving.

3. Which of the following are the units of temperature?

Degree Celsius
Fahrenheit
Kelvin
1, 2
1, 3
2, 3
All the above

Explanation

There are three units which are used to measure the temperature: Degree Celsius, Fahrenheit and Kelvin.

Degree Celsius: Celsius is written as°C and read as degree. For example, 20°C; it is read as twenty degree Celsius. Celsius is called as Centigrade as well.

Fahrenheit: Fahrenheit is written as °F for example 25°F; it is read as twenty-five degree Fahrenheit.

4. Which of the following is the SI unit of temperature?

Degree Celsius
Fahrenheit
Kelvin
All the above

Explanation

Kelvin is written as K. For example: 100K; it is read as hundred Kelvin. The SI unit of temperature is kelvin (K).

5. Assertion(A): The temperature of the object is well approximated with the kinetic energy of the

substances.

Reason(R): The high temperature means that the molecules within the object are moving at a faster rate.

Both (A) and (R) are correct, but (R) does not explain (A)
Both (A) and (R) are wrong
Both (A) and (R) are correct and (R) explains (A)
(A) is Correct and (R) is wrong

Explanation

The temperature of the object is well approximated with the kinetic energy of the substances. The high temperature means that the molecules within the object are moving at a faster rate. Molecules in any substance are very small to analyse and calculate its movement (Kinetic energy) in order to measure its temperature. You must use an indirect method to measure the kinetic energy of the molecules of a substance.

6. When liquid is heated it____, when cooled it gets_____

Expand, Expand
Contract, Expand
Expand, Contract
Contract, Contract

Explanation

In a thermometer, when liquid gets heat, it expands and when it is cooled down, it contracts. It is used to measure temperature. Like solid and liquid objects, the effect of heat is also observed on gaseous objects.

7.____ is the most common instrument to measure temperature

Anemometer
Thermometer
Galvanometer
Wattmeter

Explanation

Thermometer is the most common instrument to measure temperature. There are various kinds of thermometers. Some of them are like glass tubes which look thin and are filled with some kind of liquid.

8. Assertion(A): Mostly Alcohol and Mercury are used in thermometers as they remain in liquid form even with a change of temperature in them

Reason(R): A small change in the temperature causes change in volume of a liquid

Both (A) and (R) are correct, but (R) does not explain (A)
Both (A) and (R) are wrong
Both (A) and (R) are correct and (R) explains (A)
(A) is Correct and (R) is wrong

Explanation

Mostly Alcohol and Mercury are used in thermometers as they remain in liquid form even with a change of temperature in them. A small change in the temperature causes change in volume of a liquid. We measure this temperature by measuring expansion of a liquid in thermometer.

9. Which of the following properties of Mercury?

Its expansion is not uniform
It is opaque and shining.
It is a good conductor of heat
1, 2
1, 3
2, 3
All the above

Explanation
Properties of Mercury:-

Its expansion is uniform. (For equal amounts of heat, it expands by equal lengths.)
It is opaque and shining.
It does not stick to the sides of the glass tube.
It is a good conductor of heat.

10. What is the boiling point of Mercury?

320 °C
257 °C
357 °C
157°C

Explanation

Mercury has a high boiling point (357°C) and a low freezing point (−39°C). Hence a wide range of temperatures can be measured using a mercury thermometer.

11. Which of the following are the features of Alcohol?

The freezing point of alcohol is less than −100°C.
Its expansion per degree Celsius rise in temperature is very large
It can be coloured brightly and hence is easily visible
1, 2
1, 3
2, 3
All the above

Explanation

Properties of Alcohol

The freezing point of alcohol is less than −100°C. So, it can be used to measure very low temperatures
Its expansion per degree Celsius rise in temperature is very large.
It can be coloured brightly and hence is easily visible

12. Which of the following statement is correct?

All clinical thermometers have a kink that prevents the mercury from flowing back into the bulb when the thermometer is taken out of the patient’s mouth, so that the temperature can be noted conveniently
A clinical thermometer indicates temperatures from a minimum of 35°C or 94°F to a maximum of 42°C or 108°F.
1 alone
2 alone
1, 2
None

Explanation

Clinical Thermometer are used to measure the temperature of a human body, at home, clinics and hospitals. All clinical thermometers have a kink that prevents the mercury from flowing back into the bulb when the thermometer is taken out of the patient’s mouth, so that the temperature can be noted conveniently. There are temperature scales on either side of the mercury thread, one in Celsius scale and the other in Fahrenheit scale. Since the Fahrenheit scale is more sensitive than the Celsius scale, body temperature is measured in F only. A clinical thermometer indicates temperatures from a minimum of 35°C or 94°F to a maximum of 42°C or 108°F.

13. Before using the Clinical thermometer mercury level should be below_____ °C

Explanation

Precautions to be Followed While Using a Clinical Thermometer:

The thermometer should be washed before and after use, preferably with an antiseptic solution.
Jerk the thermometer a few times to bring the level of the mercury down.
Before use, the mercury level should be below 35°C or 94°F.
Do not hold the thermometer by its bulb
Keep the mercury level along your line of sight and then take the reading.
Handle the thermometer with care. If it hits against some hard object, it may break.
Do not place the thermometer in a hot flame or in the hot sun.

14. A laboratory thermometer has only the Celsius scale ranging from ___°C to ____°C

10, 110
– 10, 100
35, 100
-35, 100

Explanation

Precautions to be Followed While Using a Laboratory Thermometer:

Do not tilt the thermometer while measuring the temperature. Place it upright
Note the reading only when the bulb has been surrounded by the substance from all sides
A laboratory thermometer has only the Celsius scale ranging from −10°C to 110°C.

15. Which of the following statement is correct?

Laboratory thermometers are used to measure the temperature in school and other laboratories for scientific research.
They are also used in the industry as they can measure temperatures higher than what clinical thermometers can record
The stem and the bulb of a lab thermometer are longer when compared to that of a clinical thermometer
1, 2
1, 3
2, 3
All the above

Explanation

Laboratory thermometers are used to measure the temperature in school and other laboratories for scientific research. They are also used in the industry as they can measure temperatures higher than what clinical thermometers can record. The stem and the bulb of a lab thermometer are longer when compared to that of a clinical thermometer and there is no kink in the lab thermometer.

16. What is the average internal temperature of human?

37°C
34°C
27°C
47°C

Explanation

In humans, the average internal temperature is 37°C (98.6°F), though it varies among individuals. However, no person always has exactly the same temperature at every moment of the day. Temperatures cycle regularly up and down through the day according to activities and external factors.

17. Which of the following statement about Clinical Thermometer is correct?

Clinical thermometer is scaled from 25°C to 42°C or from 94°F to 108°F.
Temperature can be read after removing the thermometer from armpit or mouth.
To lower the mercury level jerks are given.
1, 2
1, 3
2, 3
All the above

Explanation

18. Which of the following statement about Laboratory Thermometer is incorrect?

Laboratory thermometer is generally scaled from 10°C to 110°C.
Mercury level falls on its own as no kink is present
No need to give jerk to lower the mercury level.
Temperature is read while keeping the thermometer in the source of temperature

Explanation

19. Which of the following statement is correct?

Digital thermometers are available which use mercury along with a sensor
Digital thermometers are mainly used to take the body temperature
Mercury is a toxic substance and is very difficult to dispose of if a thermometer break.
1, 2
1, 3
2, 3
All the above

Explanation

Here is a lot of concern over the use of mercury in thermometers. Mercury is a toxic substance and is very difficult to dispose of if a thermometer break. These days, digital thermometers are available which do not use mercury. Instead, it has a sensor which can measure the heat coming out from the body directly and from that can measure the temperature of the body. Digital thermometers are mainly used to take the body temperature.

20. Assertion(A): We should not use Clinical thermometer to measure the temperature of hot milk

Reason(R): A Clinical thermometer has small temperature range

Both (A) and (R) are correct, but (R) does not explain (A)
Both (A) and (R) are wrong
Both (A) and (R) are correct and (R) explains (A)
(A) is Correct and (R) is wrong

Explanation

Alex wanted to measure the temperature of hot milk using a clinical thermometer. His teacher stopped him from doing so. We are advised not to use a clinical thermometer for measuring the temperature of any object other than human body. A Clinical thermometer has small temperature range. The glass will crack/ burst due to excessive pressure created by expansion of mercury.

21. The temperatures of the previous day reported in weather reports are measured by____

Clinical thermometer
Digital thermometer
Laboratory thermometer
Maximum _ minimum thermometer

Explanation

The maximum and minimum temperatures of the previous day reported in weather reports are measured by a thermometer called the maximum – minimum thermometer

22. After whom Celsius scale was termed?

Anders Morgan
Daniel Gabriel Celsius
Anders Celsius
Daniel Gabriel Morgan

Explanation

Celsius is the common unit of measuring temperature, termed after Swedish astronomer, Anders Celsius in 1742, before that it was known as Centigrade as thermometers using this scale are calibrated from (Freezing point of water) 0°C to 100°C (boiling point of water). In Greek, ‘Centium’ means 100 and ‘Gradus’ means steps, both words make it centigrade and later Celsius.

23. Freezing point of water is taken as ___°F

Explanation

Fahrenheit is a Common unit to measure human body temperature. It is termed after the name of a German Physicist Daniel Gabriel Fahrenheit. Freezing point of water is taken as 32°F and boiling point 212°F. Thermometers with Fahrenheit scale are calibrated from 32°F to 212°F.

24. Kelvin scale is termed after____

Lord Celsius
Lord Kelvin
Lord Fahrenheit
Andres Kelvin Morgan

Explanation

Kelvin scale is termed after Lord Kelvin. It is the SI unit of measuring temperature and written as K also known as absolute scale as it starts from absolute zero temperature.

25. Match the following:

Boiling point of water (°C) 1. 37
Boiling point of water (°F) 2. 100
Mean temperature of human body (°C) 3. 212
Room temperature (°C) 4. 72
2, 1, 3, 4
2, 3, 1, 4
2, 3, 4, 1
4, 1, 2, 3

Explanation

26. Which of the following are equal?

(F – 32)/ 9
C/5
9C
1, 3
2, 3
1, 2
None

Explanation

27. Which of the following is Absolute zero Temperature?

0 K
-273.15 °C
-459.67 °F
All the above

Explanation

28. _____maintains the coldest known natural temperature in the universe

Boomerang Nebula
Boomerang Gamora
Boomerang Wanda
Boomerang Vision

Explanation

29. Coldest natural temperature ever recorded on Earth is____

0 °C
-94.7 °F
-94.7 °C
273 °C

Explanation

30. Temperature of the Universe in the earliest moments after the Big Bang was ____

10^32 K
10^2 K
10^132 K
10^22 K

Explanation

31. Which of the following are the boiling point of water?

100 °C
212° F
373.15 K
1, 2
1, 3
2, 3
All the above

Explanation

32. Hottest natural temperature ever recorded on Earth

100 °C
56.7 °C
134.06 °C
329.85 °C

Explanation

33. Which of the following scale is used to measure temperature for day to day purpose?

Kelvin
Celsius
Fahrenheit
All the above

Explanation

Most of the people in the world use the Celsius scale to measure temperature for day to day purpose. The Kelvin scale has been designed in such a way, it is not only an absolute temperature scale, but also 1°C change is equal to a 1K change. This makes the conversion from Celsius to absolute temperature scale (Kelvin scale) easy, just the addition or subtraction of a constant 273.15.

34. United States prefer___ scale

Kelvin
Celsius
Fahrenheit
All the above

Explanation

In United States they prefer to use the Fahrenheit scale. The problem is, converting Fahrenheit to absolute scale (Kelvin) is not easy.

35. Which of the following statement is correct?

The Rankine scale was named after the Glasgow University engineer and physicist Rankine, who proposed it in 1859
It is an absolute temperature scale, and has the property of having a 1°R change is equal to a 1.5°F change.
1 alone
2 alone
1, 2
None

Explanation

The Rankine scale was named after the Glasgow University engineer and physicist Rankine, who proposed it in 1859. It is an absolute temperature scale, and has the property of having a 1°R change is equal to a 1°F change. Fahrenheit users who need to work with absolute temperature can be converted to Rankine by R= F+ 459.67

36. How much will the temperature of 68°F be in Celsius?

Explanation

C = 5x 36/ 9 = 20°C

K = C + 273.15 = 20 + 273.15 = 293.15

Thus, the temperature in Celsius = 20 degree C and in Kelvin = 293.15 K

37. At what temperature will its value be same in Celsius and in Fahrenheit?

40
– 40
20
– 20

Explanation

7th Science Lesson 8 Questions in English

8] Electricity

1. In which year Thomas Alva Edison lightened up the New York city?

1889
1882
1892
1922

Explanation

In 1882, when it was sun set in the west that miracle happened in New York city. When Thomas Alva Edison gently pushed the switch on 14,000 bulbs in 9,000 houses suddenly got lighted up. It was the greatest invention to mankind. From then the world was under the light even in the night.

2. Where was the 1^st thermal power plant commissioned in India?

Madras
Calcutta
Bombay
Bangalore

Explanation

Many countries began using electricity for domestic purposes. Seventeen years after the New York, in 1899 electricity first came to India. The Calcutta Electric Supply Corporation Limited commissioned the first thermal power plant in India on 17 April 1899

3. In Madras province were the 1^st thermal power station set up?

Koodankulam
Ennore
Basin Bridge
Erode

Explanation

Around 1900s, a thermal power station was set up at Basin Bridge in Madras city and power was distributed to the government press, general hospital, electric tramways and certain residential areas in Madras. Today electricity is a common household commodity.

4. Which of the following statement is correct?

The nucleus consists of protons and neutrons
Negatively charged electrons revolve around the nucleus in circular orbits
Neutrons have no charge
1, 2
1, 3
2, 3
All the above

Explanation

The centre of the atom is called the nucleus. The nucleus consists of protons and neutrons. Protons are positively charged. Neutrons have no charge. Negatively charged electrons revolve around the nucleus in circular orbits. Electricity is a form of energy that is associated with electric charges that exists inside the atom.

5. When getting up from the plastic chair, the___ shirt seems to be stuck to the chair

Cotton
Wollen
Nylon
Fabrics

Explanation

Comb your dry hair. Immediately after combing the dry hair, bring the comb closer to the bits of paper. what will you observe? When you are getting up from the plastic chair, the nylon shirt seems to be stuck to the chair and make crackling sound. What is the reason for the creation of the sound? A balloon sticks to wall without any adhesive after rubbing on your hand. Do you know the reason for all? In all the above activities, when a body is rubbed against some other body become charged.

6. One unit of coulomb is charge of approximately__________

6.242×10^18 protons
6.242×10^18 electrons
6.242×10^18 neutrons
Either a or b

Explanation

Electric charge is measured in a unit called coulomb. One unit of coulomb is charge of approximately 6.242×10^18 protons or electrons. Electrical charges are generally denoted by the letter `q`.

7. Which of the following statement is correct?

The flow of electric charges constitutes an electric current
The conventional symbol for current is ‘I’.
An electric current is measured by the amount of electric charge moving per unit time per unit time at any point in the circuit
1, 2
1, 3
2, 3
All the above

Explanation

The flow of electric charges constitutes an electric current. For an electrical appliance to work, electric current must flow through it. An electric current is measured by the amount of electric charge moving per unit time at any point in the circuit. The conventional symbol for current is ‘I’.

8. Which of the following about Electric Current is correct?

I = q / t
I = q .t
I = q^ t
q = I / t

Explanation

The SI unit for measuring an electric current is the ampere, which is the flow of electric charge across a surface at the rate of one coulomb per second.

I = q / t

Where I ⇒ current (in Ampere – A) q ⇒ charge (in coulomb – c) t ⇒ time taken (in seconds – s)

9. If 30 coulomb of electric charge flows through a wire in two minutes, calculate the current?

25 A
2.5 A
0.25 A
22.5 A

Explanation

Charge (q) = 30 coulomb

Time (t) = 2 min x 60s = 120 s

Current I = q/t = 30C/120s = 0.25 A

10. Which of the following statement is incorrect?

Before the discovery of electrons, scientists believed that an electric current consisted of moving positive charges.
This movement of positive charges is called conventional current
1 alone
2 alone
1, 2
None

Explanation

Before the discovery of electrons, scientists believed that an electric current consisted of moving positive charges. This movement of positive charges is called conventional current

11. Which of the following statement is correct?

After the electrons were discovered, it was known that electron flow actually takes place from the negative terminal to the positive terminal of the battery
This movement is known as electron flow
Conventional current is in the direction opposite to electron flow.
1, 2
2, 3
1, 3
All the above

Explanation

After the electrons were discovered, it was known that electron flow actually takes place from the negative terminal to the positive terminal of the battery. This movement is known as electron flow. Conventional current is in the direction opposite to electron flow.

12. Electric current is measured using a device called_____

Wattmeter
Voltmeter
Ammeter
Galvanometer

Explanation

Electric current is measured using a device called ammeter. The terminals of an ammeter are marked with + and – sign. An ammeter must be connected in series in a circuit.

13. 1 milliampere (mA) =

1/10000 ampere
1/1000 ampere
1/100 ampere
1/1000000 ampere

Explanation

Instruments used to measure smaller currents, in the milli ampere or micro ampere range, are designated as milli ammeters or micro ammeters.

14. If 0.002A current flows through a circuit, then convert the current in terms of micro ampere?

2000 µA
200 µA
2 µA
2000 mA

Explanation

Given that the current flows through the circuit is 0.002A

We know that 1 A = 106 µA

0.002A = 0.002 × 106 µA

= 2 × 10-3 × 106 µA

= 2 × 103 µA

0.002A = 2000 µA

15. Assertion: An electric charge always flows from a point at higher potential to a point at lower

potential.

Reason(R): The potential difference between any two points in the circuit is the amount of energy

needed to move one unit of electric charge from one point to the other.

Both (A) and (R) are correct, but (R) does not explain (A)
Both (A) and (R) are wrong
Both (A) and (R) are correct and (R) explains (A)
(A) is Correct and (R) is wrong

Explanation

Electrical charges need energy to push them along a circuit. Water always flows from higher to lower ground. Similarly, an electric charge always flows from a point at higher potential to a point at lower potential. An electric current can flow only when there is a potential difference (V) or P.D. The potential difference between any two points in the circuit is the amount of energy needed to move one unit of electric charge from one point to the other.

16. The SI unit of potential difference is_____

Kwh
V
A/s
Watt

Explanation

The term mentioned in the board volt is the measurement for the electric potential difference. The SI unit of potential difference is volt (V). potential difference between two points is measured by using a device called voltmeter.

17. Which of the following statement is correct?

An electrical component resists or hinders the flow of electric charges, when it is connected in a circuit.
The lower the resistance in a component, the higher the potential difference needed to move electric charge through the component
Resistance of a component is the ratio of the potential difference across it to the current

flowing through it

1, 2
1, 3
2, 3
All the above

Explanation

An electrical component resists or hinders the flow of electric charges, when it is connected in a circuit. In a circuit component, the resistance to the flow of charge is similar to how a narrow channel resists the flow of water. The higher the resistance in a component, the higher the potential difference needed to move electric charge through the component. We can express resistance as a ratio. Resistance of a component is the ratio of the potential difference across it to the current flowing through it

V = I/ R

18. The S.I unit of resistance is____

A
Ohm
Volt
Watt/s

Explanation

Resistance of a component is the ratio of the potential difference across it to the current flowing through it. The S.I unit of resistance is ohm. Greater the ratio of V to I, the greater is the resistance.

19. The S.I Unit of electrical conductivity is_____

Siemens
Siemens/s
Siemens/m
ohm-metre

Explanation

Electrical conductivity or specific conductance is the measure of a material’s ability to conduct an electric current. It is commonly represented by the Greek letter σ (sigma). The S.I Unit of electrical conductivity is Siemens/meter(S/m).

20. Which of the following statement is correct?

Electrical resistivity is a fundamental property of a material that quantifies how strongly that material opposes the flow of electric current
The SI unit of electrical resistivity is the ohm/metre
1 alone
2 alone
1, 2
None

Explanation

Electrical resistivity (also known as specific electrical resistance, or volume resistivity) is a fundamental property of a material that quantifies how strongly that material opposes the flow of electric current. The SI unit of electrical resistivity is the ohm-metre (Ω.m).

21. Match the following with their Resistivity:

Silver 1. 1.72×10^-8
Annealed Copper 2. 1.59×10^-8
Copper 3. 1.68×10^-8
Aluminium 4. 2.82×10^-8
2, 1, 3, 4
2, 1, 4, 3
2, 3, 1, 4
3, 1, 2, 4

Explanation

22. Match the following

Pump 1. Resistance
Pressure 2. Battery
Some dust and rust that plug up the pipe 3. Voltage generated by battery
Wire 4. Pipe
4, 2, 1, 3
2, 3, 1, 4
1, 4, 3, 2
1, 2, 4, 3

Explanation

Water flowing through pipes is pretty good mechanical system that is a lot like an electrical circuit. This mechanical system consists of a pump pushing water through a closed pipe. Imagine that the electrical current is similar to the water flowing through the pipe. The following parts of the two systems are related:

The pipe is like the wire in the electric circuit and the pump is like the battery
The pressure generated by the pump drives water through the pipe.
The pressure is like the voltage generated by the battery which drives electrons through the electric circuit
Suppose, there are some dust and rust that plug up the pipe and slow the flow of water, creating a pressure difference from one end to the other end of the pipe. In similar way, the resistance in the electric circuit resists the flow of electrons and creates a voltage drop from one end to the other. Energy loss is shown in the form of heat across the resistor.

23. Which of the following statement is correct?

Electric cell converts chemical energy into electrical energy
Electric cells have two terminals.
In addition to electro chemical, we use electro thermal source for generating electricity for large scale use
1, 2
2, 3
1, 3
All the above

Explanation

The sources which produce the small amount of electricity for shorter periods of time is called as electric cell or electro chemical cells. Electric cell converts chemical energy into electrical energy. In addition to electro chemical, we use electro thermal source for generating electricity for large scale use. It has two terminals. When electric cells are used, a chemical reaction takes place inside the cells which produces charge in the cell.

24. Which of the following statement about primary cell is correct?

The dry cell commonly used in torches
It can be recharged after use.
1 alone
2 alone
1, 2
None

Explanation

The dry cell commonly used in torches is an example of a primary cell. It cannot be recharged after use.

25. Which of the following are examples of Secondary cells?

Lithium cylindrical cells
Button cells
Alkaline cells
1, 2
1, 3
2, 3
All the above

Explanation

Secondary cells are used in automobiles and generators. The chemical reaction in them can be reversed, hence they can be recharged. Lithium cylindrical cells, button cells and alkaline cells are the other types that are in use.

26. Which of the following are examples of primary cell?

Lead accumulator
Daniel cell
Lechlanche cell
1, 2
1, 3
2, 3
All the above

Explanation

27. Which of the following statement about secondary cell is correct?

The chemical reaction inside the secondary cell is reversible
It is used to operate devices such as mobile phones, cameras, computers, and emergency lights
1 alone
2 alone
1, 2
None

Explanation

28. Which of the following statement about dry cell is correct?

It is a convenient source of electricity available in portable and compact form.
It was developed in 1887 by Yei Sakizo of Japan
1 alone
2 alone
1, 2
None

Explanation

A dry cell is a type of chemical cell commonly used in the common form batteries for many electrical appliances. It is a convenient source of electricity available in portable and compact form. It was developed in 1887 by Yei Sakizo of Japan.

29. Which of the following act as electrolyte in dry cell?

Ammonium chloride
Hydrochloric acid
Sulphuric acid
Phosphoric acid

Explanation

A dry cell is a portable form of a leclanche cell. It consists of zinc vessel which acts as a negative electrode or anode. The vessel contains a moist paste of saw dust saturated with a solution of ammonium chloride and zinc chloride. The ammonium chloride acts as an electrolyte.

30. Which of the following statement about dry cell is correct?

The purpose of zinc chloride is to maintain the moistness of the paste being highly hygroscopic
The carbon rod covered with a brass cap is placed in the middle of the vessel. It acts as positive electrode or cathode.
The chemical action inside the cell is the same as in leclanche cell
1, 2
1, 3
2, 3
All the above

Explanation

The purpose of zinc chloride is to maintain the moistness of the paste being highly hygroscopic. The carbon rod covered with a brass cap is placed in the middle of the vessel. It acts as positive electrode or cathode. It is surrounded by a closely packed mixture of charcoal and manganese dioxide (MnO2) in a muslin bag. Here MnO2 acts as depolarizer. The zinc vessel is sealed at the top with pitch or shellac. A small hole is provided in it to allow the gases formed by the chemical action to escape. The chemical action inside the cell is the same as in leclanche cell.

31. Electrolyte in the dry cell is______ in nature

Solution
Gas
Paste
Solid

Explanation

The dry cell is not really dry in nature but the quantity of water in it is very small, as the electrolyte is in the form of a paste. In other cells, the electrolyte is usually a solution.

32. Which of the following statement is correct?

Batteries are a collection of one or more cells whose chemical reactions create a flow of electrons in a circuit
Electrolyte is a substance that chemically reacts with the anode and cathode
All batteries are made up of three basic components: anode, cathode, electrolyte
1, 2
1, 3
2, 3
All the above

Explanation

Batteries are a collection of one or more cells whose chemical reactions create a flow of electrons in a circuit. All batteries are made up of three basic components: an anode (the ‘+’ side), a cathode (the ‘–’ side), and some kind of electrolyte. Electrolyte is a substance that chemically reacts with the anode and cathode.

33. Who was related with Galvani theory?

Luigi Galvani
Einstein
Newton
Cooper

Explanation

One fateful day in 1780, Italian physicist, physician, biologist, and philosopher, Luigi Galvani, was dissecting a frog attached to a brass hook. As he touched the frog’s leg with an iron scapel, the leg twitched. Galvani theorized that the energy came from the leg itself, but his fellow scientist, Alessandro Volta, believed otherwise.

34. Who is often attributed to invention of the modern battery?

Alessandro Volta
Luigi Galvani
George Siemen ohm
Newton

Explanation

The invention of the modern battery is often attributed to Alessandro Volta. It actually started with a surprising accident involving the dissection of a frog.

35. In a cell, the longer line denotes the_____

Positive
Negative
Neutral
None

Explanation

In a cell, the longer line denotes the positive (+) terminal and the short line denotes the negative (-) terminal. We shall use these symbols to show components in the circuits we draw. Such diagrams are called circuit diagrams.

36. The following figure is a:

Open circuit
Parallel circuit
Series circuit
Mixed circuit

Explanation

Two kinds of circuits can be made with two bulbs and a cell. In this experiment we shall make one of them and study it. Look at the circuit with two bulbs, and a cell and a switch given here (Figure). It is clear from the circuit diagram, that the two bulbs are connected one after the other. The circuit diagram shows the sequence of the bulbs and cell, not their real position. The way in which the bulbs have been connected in this circuit is called series connection.

37. The following figure is a:

Open circuit
Parallel circuit
Series circuit
Mixed circuit

Explanation

Figure – shows a circuit in which two bulbs are connected in different places. This is a second type of circuit. Two bulbs in this circuit are said to be connected in parallel and such circuits are called parallel circuits.

38. Which of the following statement is correct?

An atom, in turn, contains electrically charged particles
Many of these particles are fixed to the atoms but in conductors (such as all metals) there are lots of particles that are not held to any particular atom but are free to wander around randomly in the metal.
1 alone
2 alone
1, 2
None

Explanation

We know that all materials are made up of the basic building block, the ‘atom’. An atom, in turn, contains electrically charged particles. Many of these particles are fixed to the atoms but in conductors (such as all metals) there are lots of particles that are not held to any particular atom but are free to wander around randomly in the metal. These are called ‘free charge’.

39. A short circuit is simply a____ connection between the two conductors supplying electrical power to any circuit

High resistance
Low resistance
Open circuit
Closed circuit

Explanation

You might have observed the spark in the electric pole located nearby your house. Do you know the cause of this electric spark? This is due to the short circuiting of electricity along its path. A short circuit is simply a low resistance connection between the two conductors supplying electrical power to any circuit. Arc welding is a common example of the practical application of the heating due to a short circuit.

40. Which of the following statement is correct?

Based on the property of conductance of electricity, substances are classified into two types, namely, Conductors and Insulators
The electrons of different types of atoms have different degrees of freedom to move around.
1 alone
2 alone
1, 2
None

Explanation

Based on the property of conductance of electricity, substances are classified into two types, namely, Conductors and Insulators (or) bad conductors of electricity. Electrons of different types of atoms have different degrees of freedom to move around. With some types of materials, such as metals, the outermost electrons in the atoms are loosely bound and they chaotically move in the space between the atoms of that material. Because these virtually unbound electrons are free to leave their respective atoms and float around in the space between adjacent atoms, they are often called as free electrons.

41. Which of the following statement is correct?

Conductors are the materials whose atoms have electrons that are loosely bound and are free to move through the material
A good conductor has high electrical conductivity
1 alone
2 alone
1, 2
None

Explanation

Conductors are the materials whose atoms have electrons that are loosely bound and are free to move through the material. A material that is a good conductor gives very little resistance to the flow of charge (electron) on the application of external voltage. This flow of charge (electron) is what constitutes an electric current. A good conductor has high electrical conductivity.

42. The chip which are used in SIM Cards, Computers, and ATM cards are made up of____

Conductors
Semiconductors
Insulators
None

Explanation

The chip which are used in SIM Cards, Computers, and ATM cards are made up of semiconductors namely, silicon and germanium because of their electrical conductivity lies between a conductor and an insulator.

43. Assertion(A): Rubber is a insulator, it is a non-conductor of electricity.

Reason(R): The rubber eraser does not allow electric current to pass through it

Both (A) and (R) are correct, but (R) does not explain (A)
Both (A) and (R) are wrong
Both (A) and (R) are correct and (R) explains (A)
(A) is Correct and (R) is wrong

Explanation

An insulator gives a lot of resistance to the flow of charge (electron). During the drift of the electrons in an object when an external voltage is applied, collisions occur between the free electrons and the atoms of the material also affect the movement of charges. These collisions mean that they get scattered. It is a combination of the number of free electrons and how much they are scattered that affects how well the metal conducts electricity. The rubber eraser does not allow electric current to pass through it. So, rubber is a non-conductor of electricity. Rubber is an insulator.

44. Which of the following statement is correct?

Wires made of copper, an electrical conductor, have very low resistance.
These wires are in turn enclosed in electrical insulators, or materials of high electrical resistance.
These materials are usually made of flexible plastic.
1, 2
1, 3
2, 3
All the above

Explanation

Wires made of copper, an electrical conductor, have very low resistance. Copper wires are used to carry current in households. These wires are in turn enclosed in electrical insulators, or materials of high electrical resistance. These materials are usually made of flexible plastic.

45. Which of the following effects does electricity have?

Heating effect
Magnetic effect
Chemical effect
1, 2
1, 3
2, 3
All the above

Explanation

The light of the bulb is thus one of the effects of electricity. There are several other important effects of electricity. We shall study some of these effects in this chapter. There are 3 main effects of electricity as,

Heating effect
Magnetic effect (Magnetism)
Chemical effect

46. Which of the following statement is correct?

When electric-current passes through a wire, the electrical energy is converted to hear
In heating appliances, the heating element is made up of materials with low melting point
The electric bulb, geyser, iron box, immersible water heater are based on this effect
1, 2
1, 3
2, 3
All the above

Explanation

When electric current passes through a wire, the electrical energy is converted to hear. In heating appliances, the heating element is made up of materials with high melting point. An example of such a material is nichrome (an alloy of nickel, iron and chromium). The heating effect of electric current has many practical applications. The electric bulb, geyser, iron box, immersible water heater are based on this effect. These appliances have heating coils of high resistance.

47. Which of the following statement is correct?

Electric fuse is a safety device which is used in household wiring and in many appliances
The fuse wire melts whenever there is overload of the current in the wire
In electrical devices, a glass fuse is often used
1, 2
1, 3
2, 3
All the above

Explanation

Electric fuse is a safety device which is used in household wiring and in many appliances. Electric fuse has a body made of ceramic and two points for connecting the fuse wire. The fuse wire melts whenever there is overload of the current in the wire. This breaks the circuit and helps in preventing damage to costly appliances and to the wiring. In electrical devices, a glass fuse is often used. This is a small glass tube, in which lies the fuse wire.

48. Assertion(A): MCBs have been replacing electric fuse from wirings at most of the places

Reason(R): The electric fuse has a big practical problem

Both (A) and (R) are correct, but (R) does not explain (A)
Both (A) and (R) are wrong
Both (A) and (R) are correct and (R) explains (A)
(A) is Correct and (R) is wrong

Explanation

MCBs have been replacing electric fuse from wirings at most of the places. The electric fuse has a big practical problem. Whenever the wire fuses, one needs to replace the wire to resume electric supply. More often than not, this proves to be a cumbersome task. Miniature circuit breakers break the circuit automatically. One just needs to switch it on to resume the electric supply. Many models of MCBs have a built-in mechanism by which the electric supply is automatically resumed.

49. Who discovered the Magnetic Effect of electricity?

Faraday
Hans Christian Oersted
Albert Einstein
Michel O’ Dwyer

Explanation

The next effect of electric current is Magnetism. In 1819, Hans Christian Oersted discovered the electricity that has a magnetic effect. The experiment in activity-5 will help you understand the magnetic effect of electric current.

50. Which of the following statement is correct?

Magnetic effect of electric current has been used in making powerful electromagnets
Electro magnets are used in many appliances that we use in our day to day life, namely, electric bell, cranes and telephone
Electromagnets are also used to remove splinters of steel or iron in hospitals dealing with eye injuries
1, 2
1, 3
2, 3
All the above

Explanation

Magnetic effect of electric current has been used in making powerful electromagnets. Electromagnets are also used to remove splinters of steel or iron in hospitals dealing with eye injuries. Electro magnets are used in many appliances that we use in our day to day life, namely, electric bell, cranes and telephone.

51. Which of the following statement is correct?

In telephones, a changing magnetic effect causes a thin sheet of metal (diaphragm) to vibrate
The diaphragm is made up a metal that can be attracted to magnets.
1 alone
2 alone
1, 2
None

Explanation

In telephones, a changing magnetic effect causes a thin sheet of metal (diaphragm) to vibrate. The diaphragm is made up a metal that can be attracted to magnets.

The diaphragm is attached to spring that is fixed to the earpiece
When a current-flows through the wires, the soft – iron bar becomes an electromagnet.
The diaphragm becomes attracted to the electromagnet.
As the person on the other end of the line speaks, his voice cause the current in the circuit to change. This causes the diaphragm in the earpiece to vibrate, producing sound.

52. Which of the following were invented by Edison?

Electric bulb
Electric motor
Gramophone
Kinetoscope
1, 3, 4
2, 3, 4
1, 2, 3
All the above

Explanation

Edison was an American Scientist and Industrialist. He invented many instruments like Electric bulb, electric motor, gramophone and kinetoscope. He was known as for taking the world of darkness to brightness crossing all the obstacles in life.

53. For whose death, the light of “Statue of Liberty” in New York was turned off?

Einstein
Edison
Newton
Tesla

Explanation

As a mark of respect to Edison on his death, the light of “Statue of Liberty” in New York was turned off. Except the road lights of Chicago and Broadway, all the lights in the city were turned off.

54. _______ wire coil was used by Edison in his first electric bulb

Gold
Titanium
Platinum
Silver

Explanation

Thomas Alva Edison invented a commercially viable electric bulb. This was exhibited in 1897. He used a platinum wire coil in a vacuum glass and discovered the first electric bulb in 1879.