Types Of Chemical Reactions Book Back Questions 10th Science Lesson 10

10th Science Lesson 10

10] Types Of Chemical Reactions

Book Back Questions with Answer and Do You Know Box Content

Do You Know?

A balanced chemical equation is the simplified representation of a chemical reaction which describes the chemical composition, physical state of the reactants and the products and the reaction conditions.

The phases or the physical state of the substances in a chemical reaction are denoted in short form within a bracket, as the subscript of the formula, of the respective substances. For example, when solid potassium reacts with liquid water, it produces hydrogen gas and potassium hydroxide solution. All these information of the reaction is given in the chemical equation as shown below:

2K_(S) + 2H₂O_(I) 🡪 2KOH_(aq) + H_2(g)

Symbol	Phase or physical state
S	Solid
L	Liquid
G	Gas
Aq	Aqueous Solution

A solution of slaked lime is used for white washing walls. Calcium hydroxide reacts slowly with the carbon dioxide in air to form a thin layer of calcium carbonate on the walls. Calcium carbonate is formed after two to three days of white washing and gives a shiny finish to the walls. It is interesting to note that the chemical formula for marble is also CaCO₃

Ca(OH) _2(aq) + CO_2(g) 🡪 CaCO_3(S) + H₂O_(I)

Slaked lime Carbon di oxide Calcium Carbonate Water

If hydrogen peroxide is poured on a wound, it decomposes into water and oxygen. The gaseous oxygen bubbles away as it is formed and thus prevent the formation of H₂O₂.

Food kept at room temperature spoils faster than that kept in the refrigerator. In the refrigerator, the temperature is lower than the room temperature and hence the reaction rate is less.

Aerated soft drinks contain dissolved carbon dioxide in a pop bottle (Soda). When the bottle is sealed, the dissolved carbon dioxide (in the form of carbonic acid) and gaseous CO_2­ are in equilibrium with each other. When you open the bottle, the gaseous CO₂ can escape. So, the dissolved CO₂ begins to undissolve back to the gas phase trying to replace the gas that was lost, when you opened the bottle. That’s why if you leave it open long enough, it will go ‘flat’. All the CO₂ will be gone, blown away in the air.

Choose the best answers:

1. H_2(g) + Cl_29(g) 🡪 2HCl_(g) is a

(a) Decomposition reaction

(b) Combination reaction

(c) Single Displacementreaction

(d) Double Displacementreaction

2. Photolysis is a decomposition reaction caused by ______________

(a) Heat

(b) Electricity

(c) Light

(d) Mechanical energy

3. A reaction between carbon and oxygen is represented by C_(S) + O_2(g) 🡪 CO_2(g) + Heat. In which of the type(s), the above reaction can be classified?

(i) Combinationreaction (ii) Combustionreaction

(iii) Decompositionreaction (iv) Irreversiblereaction

(a) (i) and (ii)

(b) (i) and (iv)

(c) (i), (ii) and (iii)

(d) (i), (ii) and (iv)

4. The chemical equation Na₂SO_4(aq) + BaCl_2(aq) 🡪 BaSO_4(S) ↓ + 2NaCl_(aq) represents which of the following types of reaction?

(a) Neutralization

(b) Combustion

(c) Precipitation

(d) Single displacement

5. Which of the following statements are correct about a chemical equilibrium?

(i) It is dynamic in nature

(ii) The rate of the forward and backward reactions is equal at equilibrium

(iii) Irreversible reactions do not attain chemical equilibrium

(iv) The concentration of reactants and products may be different

(a) (i), (ii) and (iii)

(b) (i), (ii) and (iv)

(c) (ii), (iii) and (iv)

(d) (i), (iii) and (iv)

6. A single displacement reaction s represented by X_(S) + 2HCl_(aq) 🡪 XCl_2(aq) + H_2(g). Which of the following(s) could be X.

(i) Zn (ii) Ag (iii) Cu (iv) Mg

(a) (i) and (ii)

(b) (ii) and (iii)

(c) (iii) and (iv)

(d) (i) and (iv)

7. Which of the following is not an “element + element 🡪 compound” type reaction?

(a) C_(S) + O_2(g) 🡪 CO_2(g)

(b) 2K_(S) + Br_2(I) 🡪 2KBr_(S)

(c) 2CO_(g) + O_2(g) 🡪 2CO_2(g)

(d) 4Fe_(S) + 3O_2(g) 🡪 2Fe₂O_3(S)

8. Which of the following represents a precipitation reaction?

(a) A_(s) + B_(s) 🡪 C_(s) + D_(s)

(b) A_(s) + B_(aq) 🡪 C_(aq) + D_(/)

(c) A_(aq) + B_(aq) 🡪 C_(s) + D_(aq)

(d) A_(aq) + B_(s) 🡪 C_(aq) + D_(/)

9. The pH of a solution is 3. Its [OH^–] concentration is

(a) 1 x 10^-3 M

(b) 3M

(c) 1 x 10^-11M

(d) 11M

10. Powdered CaCO₃ reacts more rapidly than flaky CaCO₃ because of ___________

(a) Large surface area

(b) High pressure

(c) High concentration

(d) High temperature

Fill in the blanks:

1. A reaction between an acid and a base is called ____________

1. Combination
2. Neutralization
3. Decomposition
4. None of the above

2. When lithium metal is placed in hydrochloric acid, ___________ gas is evolved.

1. H₂
2. H₃
3. _­H₂O
4. None of the above

3. The equilibrium attained during the melting of ice is known as _______________

1. Chemical
2. Biological
3. Physical
4. None of the above

4. The pH of a fruit juice is 5.6. If you add slaked lime to this juice, its pH _____________ (increase/decrease)

1. Increase
2. Decrease
3. Remains the same
4. None of the above

5. The value of ionic product of water at 25^oC is ____________

1.  1 × 10^-14 mol² dm^-6
2. 1 × 10^-14 mol² dm^-7
3. 1 × 10^-54 mol² dm^-6
4. None of the above

6. The normal pH of human blood is ____________

1. 7.5
2. 7.6
3. 7.4
4. None of the above

7. Electrolysis id type of __________ reaction.

1. Combination
2. Neutralization
3. Decomposition
4. None of the above

8. The number of products formed in a synthesis of reaction is __________

1. 1
2. 2
3. 3
4. 4

9. Chemical volcano is an example for ______________ type of reaction.

1. Combination
2. Neutralization
3. Decomposition
4. None of the above

10. The ion formed by dissolution of H⁺ in water is called ____________

1. Oxygen ion
2. Hydronium ion
3. Carbon ion
4. None of the above

Match the following:

1. Identify the types of reaction:

REACTION	TYPE
NH4OH(aq) + CH3COOH(aq) 🡪 CH3CHCOONH4(aq) + H2O(I)	Single Displacement
Zn(S) + CuSO4(aq) 🡪 ZnSO4(aq) + Cu(S)	Combustion
ZnCO3(S) Heat🡪ZnO(S) + CO2(g)	Neutralisation
C2H4(g) + 4O2(g) 🡪 2CO2(g) + 2H2O(g) +Heat	Thermal decomposition

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

1. Silver metal can displace hydrogen gas from nitric acid.

2. The pH of rain water containing dissolved gases like SO₄, CO₂, NO₂ will be less than 7.

3. At the equilibrium of a reversible reaction, the concentration of the reactants and the products will be equal.

4. Periodic removal of one of the products of a reversible increases the yield.

5. On dipping a pH paper in a solution, it turns into yellow. Then the solution is basic.

Answers:

Choose the best answer:

1.Decomposition reaction 2. Light 3. (i), (ii) and (iv) 4. Precipitation 5. (i),(ii) and(iii)

1. 6.(i) and (iv) 7. 2CO_(g) + O_2(g) → 2CO_2(g)

8. A_(aq) + B_(aq) → C_(s) + D_(aq) 9. 1 × 10^-11 M 10.

1. large surface area

Fill in the blanks:

1.Neutralization 2. H₂ 3. physical equilibrium 4. increases to ‘7’ 5.

1. 1 × 10^-14 mol² dm
   • • • 1. 6. 7.4 7. Decomposition 8. 1

9. Decomposition 10.

1. Hydronium ion

Match the following:

1.Neutralisation 2. Single Displacement 3. Thermal decomposition 4. Combustion

True or False:

1. False – Silver cannot displace H₂ from HNO₃ acid, since it is placed below hydrogen in the activity series.

2.True

3.False – At equilibrium the concentration of the reactants and products do not change it remains constant, but the concentration of the reactants and the products will not be equal.

4.True

5.False – The solution is neutral if the solution is basic it will be green in colour.