Types of Chemical Reactions

Samacheer Book Back Questions And Answers For Science Standard 10 “Types of Chemical Reactions“

I. Choose the correct answer:
1. H_2(g) + Cl_29(g) → 2HCl_(g) is a
a. Decomposition Reaction
b. Combination Reaction
c. Single Displacement Reaction
d. Double Displacement Reaction

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) + O2(g) → CO_2(g) + Heat. In which of the type(s), the above reaction can be classified?
(i) Combination Reaction
(ii) Combustion Reaction
(iii) Decomposition Reaction
(iv) Irreversible Reaction

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. Neutralisation
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 are 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 is 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.

Choose the best pair.
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(l) → 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_(l)
c. A_(aq) + B_(aq) → C_(s) + D_(aq)
d. A_(aq) + B_(s) → C_(aq) + D_(l)

9. The pH of a solution is 3. Its [OH^–] concentration is
a. 1 × 10^–3 M
b. 3 M
c. 1 × 10^–11 M
d. 11 M

10. Powdered CaCO₃ reacts more rapidly than flaky CaCO3 because of _____.
a. large surface area
b. high pressure
c. high concentration
d. high temperature

II. Fill in the blanks:
1. A reaction between an acid and a base is called _____.
2. When lithium metal is placed in hydrochloric acid, _____ gas is evolved.
3. The equilibrium attained during the melting of ice is known as _____.
4. The pH of a fruit juice is 5.6. If you add slaked lime to this juice, its pH _____ (increse/decrese)
5. The value of ionic product of water at 250 C is _____.
6. The normal pH of human blood is _____
7. Electrolysis is type of _____ reaction
8. The number of products formed in a synthesis reaction is _____.
9. Chemical volcano is an example for _____ type of reaction
10. The ion formed by dissolution of H⁺ in water is called _____.

Answers:
1. neutralization
2. hydrogen
3. physical equilibrium
4. Increases
5. 1.00 x 10^-14
6. 7.35 to 7.45
7. decomposition
8. one
9. decomposition
10. Hydronium ion

III. Match the following:
Identify the types of reaction
REACTION                                                                                                       TYPE
1. NH₄OH_(aq) + CH₃COOH_(aq) → CH₃COONH_4(aq) + H₂O_(l)        A. Single Displacement
2. Zn_(s) + CuSO_4(aq) → ZnSO_4(aq) + Cu_(s)                                       B. Combustion
3. ZnCO_3(s) + Heat → ZnO_(s) + CO_2(g)                                             C. Neutralisation
4. C₂H_4(g) + 4O_2(g) → 2CO_2(g) + 2H₂O_(g) + Heat                           D. Thermal decomposition

Answers:
1. A
2. B
3. C
4. D

IV. True or False: (If false give the correct statement)
1. Silver metal can displace hydrogen gas from nitric acid.
2. The pH of rain water containing dissolved gases like SO₃, 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. Periodical removal of one of the products of a reversible reaction increases the yield.
5. On dipping a pH paper in a solution, it turns into yellow. Then the solution is basic.

Answers:
1. False (Silver metal will not be displace hydrogen gas from nitric acid)
2. True
3. False (At the equilibrium of a reversible reaction, there will be no change in the concentration of the reactants and in products)
4. True
5. False (On dipping a pH paper in a solution, it turns into yellow. Then the solution is natural)

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