WORKSHEET ON ELECTROCHEMISTRY

 

Here are 20 multiple-choice questions (MCQs) based on the chapter "Electrochemistry" from Class 12 NCERT for board exam practice:

MCQs

1. The unit of cell potential (emf) is: a) Ampere
   b) Volt
   c) Coulomb
   d) Ohm

2. The electrode potential of a metal depends on: a) Nature of the metal
   b) Concentration of metal ions in solution
   c) Temperature
   d) All of the above

3. For a galvanic cell, the overall cell reaction is spontaneous if the cell potential is: a) Positive
   b) Negative
   c) Zero
   d) Unaffected by temperature

4. Which of the following is a primary cell? a) Lead storage battery
   b) Fuel cell
   c) Dry cell
   d) Nickel-cadmium cell

5. In an electrolytic cell, the reaction at the cathode is: a) Oxidation
   b) Reduction
   c) Neutralization
   d) Redox

6. Which of the following statements is true for the Nernst equation? a) It relates the cell potential to concentration
   b) It is applicable only for electrolytic cells
   c) It only applies to ideal solutions
   d) It is independent of temperature

7. The standard reduction potential for a half-cell is measured under which condition? a) 1 M concentration, 1 atm pressure, 25°C
   b) 0.1 M concentration, 1 atm pressure, 100°C
   c) 2 M concentration, 2 atm pressure, 0°C
   d) 1 M concentration, 1 atm pressure, 50°C

8. The electrochemical equivalent of a substance is defined as: a) The number of electrons gained
   b) The amount of substance deposited per unit charge
   c) The amount of energy released
   d) The equivalent weight of the substance

9. Which of the following statements is true for a galvanic cell? a) The anode is positive
   b) The anode is negative
   c) Electrons flow from cathode to anode
   d) Reduction occurs at the anode

10. In a Daniell cell, zinc is dipped in ZnSO₄ solution, and copper is dipped in CuSO₄ solution. During the reaction: a) Zn²⁺ ions are reduced
    b) Cu²⁺ ions are oxidized
    c) Zn is oxidized to Zn²⁺
    d) Cu is reduced to Cu²⁺

11. The relationship between Gibbs free energy (ΔG) and cell potential (E°) is given by: a) ΔG = nFE°
    b) ΔG = -nFE°
    c) ΔG = nRT ln E°
    d) ΔG = nFE° ln E°

12. Which law is used to determine the amount of substance deposited during electrolysis? a) Ohm’s Law
    b) Faraday’s Law
    c) Hess's Law
    d) Boyle's Law

13. The standard cell potential $E^\circ_{\text{cell}}$ for the reaction $Cu^{2+} + Zn \rightarrow Cu + Zn^{2+}$ is: a) 1.10 V
    b) 0.34 V
    c) 0.76 V
    d) 2.20 V

14. In the electrolysis of aqueous NaCl, the product obtained at the anode is: a) H₂
    b) Cl₂
    c) NaOH
    d) Na

15. In electrochemical cells, the salt bridge is used to: a) Allow the flow of electrons
    b) Maintain electrical neutrality
    c) Increase the cell potential
    d) Accelerate the reaction

16. Which of the following will not affect the conductivity of a solution? a) Concentration of ions
    b) Nature of solvent
    c) Temperature
    d) Color of the solution

17. The conductance of a solution is given by the expression: a) $G = \frac{1}{R}$
    b) $G = R$
    c) $G = \frac{R}{\lambda}$
    d) $G = I \times t$

18. If the molar conductance of a solution increases with dilution, the solution is: a) Strong electrolyte
    b) Weak electrolyte
    c) Salt solution
    d) Pure water

19. Which of the following is true for the cell potential of a concentration cell? a) It is always positive
    b) It is zero when the concentrations are equal
    c) It is independent of temperature
    d) It depends only on the nature of the electrodes

20. The potential of a hydrogen electrode in contact with hydrogen gas at 1 atm and 1 M H⁺ ion concentration is: a) 1 V
    b) 0.34 V
    c) 0.76 V
    d) 0 V

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Answers

1. (b) Volt
2. (d) All of the above
3. (a) Positive
4. (c) Dry cell
5. (b) Reduction
6. (a) It relates the cell potential to concentration
7. (a) 1 M concentration, 1 atm pressure, 25°C
8. (b) The amount of substance deposited per unit charge
9. (b) The anode is negative
10. (c) Zn is oxidized to Zn²⁺
11. (b) ΔG = -nFE°
12. (b) Faraday’s Law
13. (a) 1.10 V
14. (b) Cl₂
15. (b) Maintain electrical neutrality
16. (d) Color of the solution
17. (a) $G = \frac{1}{R}$
18. (b) Weak electrolyte
19. (b) It is zero when the concentrations are equal
20. (d) 0 V

These MCQs will help in understanding key concepts from the chapter "Electrochemistry" for Class 12 board exam preparation