Atoms And Melecules Book Back Questions 10th Science Lesson 7

10th Science Lesson 7

7] Atoms And Melecules

Book Back Questions with Answer and Do You Know Box Content

Do You Know?

Relative Atomic Mass is only a ratio, so it has no unit. If the atomic mass of an element expressed in grams, it is called as Gram Atomic Mass.

Gram Atomic Mass of hydrogen = 1 g

Gram Atomic Mass of carbon = 12 g

Gram Atomic Mass of nitrogen = 14 g

Gram Atomic Mass of oxygen = 16 g

Relative Molecular Mass is only a ratio. So, it has no unit. If the molecular mass of a compound is expressed in grams, it is called Gram Molecular Mass.

Gram Molecular Mass of water = 18 g

Gram Molecular Mass of carbon dioxide = 44 g

Gram Molecular Mass of ammonia = 17 k=g

Gram Molecular Mass of HCl = 36.5 g

Choose the best answers:

1. Which of the following has the smallest mass?

(a) 6.023 x 10²³ atoms of He

(b) 1 atom of He

(c) 2 g of He

(d) 1 mole atoms of He

2. Which of the following is a triatomic molecule?

(a) Glucose

(b) Helium

(c) Carbon dioxide

(d) Hydrogen

3. The volume occupied by 4.4 g of CO₂ at S.T.P

(a) 22.4 litre

(b) 2.24litre

(c) 0.24litre

(d) 0.1litre

4. Mass of 1 mole of Nitrogen atom is

(a) 28 amu

(b) 14 amu

(c) 28 g

(d) 14 g

5. Which of the following represents 1 amu?

(a) Mass of a C – 12 atom

(b) Mass of a hydrogen atom

(c) 1/12^th of the mass of a C – 12 atom

(d) Mass of O – 16 atom

6. Which of the following statement is incorrect?

(a) 12 gram of C – 12 contains Avogadro’s number of atoms.

(b) One mole of oxygen gas contains Avogadro’s number of molecules.

(c) One mole of hydrogen gas contains Avogadro’s number of atoms.

(d) One mole of electrons stands for 6.023 x 10²³ electrons.

7. The volume occupied by 1 mole of a diatomic gas at S.T.P is

(a) 11.2 litre

(b) 5.6litre

(c) 22.4litre

(d) 44.8litre

8. In the nucleus of ₂₀C⁴⁰, there are

(a) 20 protons and 40 neutrons

(b) 20 protons and 20 neutrons

(c) 20 protons and 40 electrons

(d) 40 protons and 200 electrons

9. The gram molecular mass of oxygen molecule is

(a) 16 g

(b) 18 g

(c) 32 g

(d) 17 g

10. 1 mole of any substance contains _____________ molecules.

(a) 6.023 x 10²³

(b) 6.023x 10^-23

(c) 3.0115x 10²³

(d) 12.046x 10²³

Fill in the blanks:

1. Atoms of different elements having ____________ mass number, but ____________ atomic numbers are called isobars.

1. Same, Same
2. Same, Different
3. Different, Different
4. Different, Same

2. Atoms of different elements having same number of ____________ are called isotones.

1. Neutrons
2. Protons
3. Electrons
4. Positrons

3. Atoms of one element can be transmuted into atoms of other element by ________________

1. Artificial Transformation
2. Atomic Transmutation
3. Artificial Transmutation
4. Atomic Transformation

4. The sum of the numbers of protons and neutrons of an atom is called its _____________

1. Atomic Number
2. Mass Number
3. Protonic Number
4. None of the Above

5. Relative atomic mass is otherwise known as ______________

1. Standard atomic weight
2. Standard atomic number
3. Standard mass number
4. None of the above

6. The average atomic mass of hydrogen is ______________ amu.

1. 1.005
2. 1.050
3. 1.008
4. 1.080

7. If a molecule is made of similar kind of atoms, then it is called ______________ atomic molecule.

1. Bi
2. Tri
3. Quadra
4. Homo

8. The number of atoms present in a molecule is called its _______________

1. Atomicity
2. Mass number
3. Charge
4. None of the above

9. One mole of any gas occupies ____________ ml at S.T.P.

1. 22200
2. 22300
3. 22400
4. None of the above

10. Atomicity of phosphorous is ______________

1. One
2. Two
3. Three
4. Four

Match the following:

1. 8 g of O₂ – 4 moles

2. 4 g of H₂ – 0.25 moles

3. 52 g of He – 2moles

4. 112 g of N₂ – 0.5moles

5. 35.5 g of Cl₂ – 13moles

State true or false. If false, correct the statement:

1. Two elements sometimes can form more than one compound.

2. Noble gases are Diatomic.

3. The gram atomic mass of an element has no unit.

4. 1 mole of Gold and Silver contain same number of atoms.

5. Molar mass of CO₂ is 42g.

Consider the statements given below and choose the correct option:

Answer the following questions using the data given below:

i) A and R are correct, R explains the A.

ii) A is correct, R is wrong.

iii) A is wrong, R is correct

iv) A and R are correct, R doesn’t explain A.

1. Assertion: The Relative Atomic mass of aluminium is 27

Reason: An atom of aluminium is 27 times heavier than 1/12^th of the mass of the C – 12 atoms.

2. Assertion: The Relative Molecular Mass of Chlorine is 35.5 a.m.u.

Reason: The natural abundance of Chlorine isotopes is not equal.

Answers:

Choose the correct answers:

1.1 mole atoms of He 2. Carbon di oxide 3. 2.24 litre 4. 14g

1. 5. 1/12^th of the mass of C-12 atom

6. One gram of C – 12 contains Avogadro’s number of atoms

1. 22.4 litres 8. 20 protons and neutrons 9. 16g 10. 6.023 X 10²³

Fill in the blanks:

1.same, different 2. Neutrons 3. artificial transmutation 4. mass number 5.

1. standard atomic weight 6. 1.008 7. Homo

8. atomicity 9. 22400 10. Four

Match the following:

1. 0.25 moles 2. 2moles 3.13 moles 4. 4 moles 5. 0.5 moles

True or False:

1. True
2. False – Noble gases are Mono atomic.
3. False – The unit of gram atomic mass of an element is gram.
4. True
5. False – Molar mass of CO₂ is 44 g.

Reason and Assertion:

1. A is wrong, R is correct