MCQs on Electrochemistry – CBSE Chemistry Class 12

Physical Chemistry – MCQ Titles (NCERT Based)
Course: CBSE Class 12 Chemistry – MCQs with Answers and Explanations

The following 50 NCERT-aligned MCQs are carefully designed as per the CBSE Class 12 Chemistry Electrochemistry chapter. Questions are arranged section-wise to cover theory, numericals, formulas, and applications, ensuring strong board exam preparation.

Section A: Basics of Electrochemistry

1. Electrochemistry deals with:

A. Heat changes in reactions
B. Chemical reactions involving electricity
C. Nuclear reactions
D. Gas laws

Correct Answer: B
Explanation: Electrochemistry studies the relationship between chemical reactions and electrical energy.

2. An electrochemical cell converts:

A. Electrical energy to chemical energy
B. Chemical energy to electrical energy
C. Heat energy to electrical energy
D. Light energy to chemical energy

Correct Answer: B
Explanation: Electrochemical cells generate electrical energy from spontaneous redox reactions.

3. Oxidation involves:

A. Gain of electrons
B. Loss of electrons
C. Gain of protons
D. Loss of neutrons

Correct Answer: B
Explanation: Oxidation is defined as loss of electrons.

4. Reduction involves:

A. Loss of electrons
B. Gain of electrons
C. Loss of protons
D. Gain of neutrons

Correct Answer: B
Explanation: Reduction is gain of electrons.

5. In a galvanic cell, oxidation occurs at:

A. Cathode
B. Salt bridge
C. Anode
D. Electrolyte

Correct Answer: C
Explanation: Oxidation always occurs at the anode.

Section B: Galvanic and Electrolytic Cells

6. In a galvanic cell, electrons flow from:

A. Cathode to anode
B. Anode to cathode
C. Salt bridge to electrodes
D. Electrolyte to electrodes

Correct Answer: B
Explanation: Electrons move from anode (oxidation) to cathode (reduction).

7. Which reaction is spontaneous?

A. Electrolysis
B. Charging of battery
C. Galvanic cell reaction
D. Electroplating

Correct Answer: C
Explanation: Galvanic cells operate via spontaneous redox reactions.

8. Salt bridge in a galvanic cell:

A. Allows electron flow
B. Maintains electrical neutrality
C. Produces current
D. Acts as electrode

Correct Answer: B
Explanation: It prevents charge buildup by allowing ion migration.

9. In electrolytic cells, electrical energy is converted into:

A. Heat energy
B. Mechanical energy
C. Chemical energy
D. Light energy

Correct Answer: C
Explanation: Electrical energy drives non-spontaneous chemical reactions.

10. An example of electrolytic process is:

A. Corrosion
B. Dry cell operation
C. Electroplating
D. Fuel cell

Correct Answer: C
Explanation: Electroplating requires external electrical energy.

Section C: Electrode Potential and EMF

11. Standard electrode potential is measured at:

A. 25°C, 1 atm, 1 M
B. 0°C, 1 atm, 1 M
C. 25°C, 1 atm, 0.1 M
D. 273 K, 2 atm

Correct Answer: A
Explanation: Standard conditions include 25°C, 1 atm pressure, and 1 M concentration.

12. The standard hydrogen electrode has potential:

A. +1.00 V
B. –1.00 V
C. 0.00 V
D. +0.76 V

Correct Answer: C
Explanation: SHE is assigned zero potential by convention.

13. EMF of a cell is:

A. Difference between electrode potentials
B. Sum of electrode potentials
C. Product of potentials
D. Ratio of potentials

Correct Answer: A
Explanation: E°cell = E°cathode − E°anode.

14. A higher reduction potential indicates:

A. Greater tendency to oxidize
B. Greater tendency to reduce
C. Lower reactivity
D. Neutral behavior

Correct Answer: B
Explanation: Higher reduction potential means greater tendency to gain electrons.

15. Unit of electrode potential is:

A. Ampere
B. Coulomb
C. Volt
D. Ohm

Correct Answer: C
Explanation: Electrode potential is measured in volts.

Section D: Nernst Equation

16. Nernst equation relates electrode potential with:

A. Temperature
B. Concentration
C. Both A and B
D. Pressure only

Correct Answer: C
Explanation: It shows dependence of potential on concentration and temperature.

17. The Nernst equation at 298 K is:

A. E = E° − (0.059/n) log Q
B. E = E° + (0.059/n) log Q
C. E = E° − (1/n) log Q
D. E = E° + log Q

Correct Answer: A
Explanation: This is the standard Nernst equation at 25°C.

18. Reaction quotient Q represents:

A. Equilibrium constant
B. Ratio of products to reactants
C. Rate constant
D. Cell constant

Correct Answer: B
Explanation: Q is the ratio of activities/concentrations of products to reactants.

19. When Q = K, cell potential becomes:

A. Maximum
B. Minimum
C. Zero
D. Infinite

Correct Answer: C
Explanation: At equilibrium, no net reaction occurs, so EMF = 0.

20. Increase in concentration of reactants:

A. Decreases cell potential
B. Increases cell potential
C. No effect
D. Stops reaction

Correct Answer: B
Explanation: Higher reactant concentration favors forward reaction.

Section E: Conductance of Electrolytic Solutions

21. Specific conductance is also called:

A. Resistance
B. Conductivity
C. Molar conductance
D. Equivalent conductance

Correct Answer: B
Explanation: Conductivity is reciprocal of resistivity.

22. Unit of conductivity is:

A. ohm
B. ohm⁻¹ cm⁻¹
C. volt
D. ampere

Correct Answer: B
Explanation: Conductivity is measured in ohm⁻¹ cm⁻¹.

23. Conductivity of solution depends on:

A. Concentration
B. Temperature
C. Nature of electrolyte
D. All of these

Correct Answer: D
Explanation: All listed factors influence ion mobility.

24. Molar conductance increases with:

A. Increase in concentration
B. Decrease in concentration
C. Increase in pressure
D. Decrease in temperature

Correct Answer: B
Explanation: Dilution increases ionic mobility.

25. Strong electrolytes show:

A. Sharp increase in molar conductance
B. Gradual increase in molar conductance
C. No change
D. Decrease in conductance

Correct Answer: B
Explanation: Strong electrolytes are already ionized.

Section F: Kohlrausch’s Law

26. Kohlrausch’s law applies to:

A. Concentrated solutions
B. Dilute solutions
C. Solid electrolytes
D. Non-electrolytes

Correct Answer: B
Explanation: It is valid at infinite dilution.

27. Limiting molar conductance is:

A. Zero concentration value
B. Conductance at 1 M
C. Conductance at infinite dilution
D. Maximum resistance

Correct Answer: C
Explanation: At infinite dilution, ions move independently.

28. Kohlrausch’s law states that:

A. Conductance depends on concentration
B. Each ion contributes independently
C. Conductance decreases with dilution
D. Resistance is constant

Correct Answer: B
Explanation: Each ion contributes its own conductance.

29. Weak electrolytes show:

A. Linear plot of Λm vs √c
B. Non-linear plot of Λm vs √c
C. Constant conductance
D. Zero conductance

Correct Answer: B
Explanation: Degree of ionization changes with dilution.

30. Limiting molar conductance helps in determining:

A. Cell constant
B. Degree of dissociation
C. Density
D. Viscosity

Correct Answer: B
Explanation: Used to calculate ionization of weak electrolytes.

Section G: Electrolysis and Faraday’s Laws

31. Faraday’s first law relates mass deposited to:

A. Voltage
B. Resistance
C. Charge passed
D. Time only

Correct Answer: C
Explanation: Mass deposited ∝ quantity of electricity.

32. Unit of Faraday constant is:

A. C mol⁻¹
B. V mol⁻¹
C. J mol⁻¹
D. A mol⁻¹

Correct Answer: A
Explanation: Faraday constant = 96485 C mol⁻¹.

33. Faraday’s second law relates mass deposited to:

A. Atomic mass
B. Equivalent mass
C. Density
D. Volume

Correct Answer: B
Explanation: Mass ∝ equivalent weight of substance.

34. Electrolysis of molten NaCl gives:

A. Na at anode
B. Cl₂ at cathode
C. Na at cathode
D. H₂ at anode

Correct Answer: C
Explanation: Na⁺ is reduced at cathode.

35. Charge on one mole of electrons is:

A. 1 C
B. 965 C
C. 96485 C
D. 100000 C

Correct Answer: C
Explanation: Known as Faraday constant.

Section H: Corrosion, Batteries, and Fuel Cells

36. Corrosion is:

A. Oxidation of metals
B. Reduction of metals
C. Neutral reaction
D. Physical change

Correct Answer: A
Explanation: Metals lose electrons during corrosion.

37. Rusting of iron is an example of:

A. Electrolytic reaction
B. Electrochemical reaction
C. Thermal reaction
D. Photochemical reaction

Correct Answer: B
Explanation: Rusting involves anodic and cathodic reactions.

38. Dry cell uses:

A. Liquid electrolyte
B. Solid electrolyte
C. Paste electrolyte
D. Gas electrolyte

Correct Answer: C
Explanation: Electrolyte is a moist paste.

39. Lead storage battery is:

A. Primary cell
B. Secondary cell
C. Fuel cell
D. Electrolytic cell

Correct Answer: B
Explanation: It can be recharged.

40. Fuel cells convert:

A. Heat to electricity
B. Chemical energy to electrical energy
C. Electrical energy to chemical energy
D. Mechanical energy to heat

Correct Answer: B
Explanation: Fuel cells generate electricity directly from chemical reactions.

Section I: Exam-Oriented MCQs

41. Which metal corrodes fastest?

A. Cu
B. Fe
C. Zn
D. Al

Correct Answer: C
Explanation: Zn has higher oxidation tendency.

42. EMF of a cell is independent of:

A. Nature of electrodes
B. Concentration
C. Distance between electrodes
D. Temperature

Correct Answer: C
Explanation: EMF depends on chemical factors, not geometry.

43. Which electrolyte shows maximum conductance?

A. CH₃COOH
B. NaCl
C. NH₄OH
D. Glucose

Correct Answer: B
Explanation: Strong electrolytes conduct better.

44. Unit of molar conductance is:

A. ohm cm
B. ohm⁻¹ cm² mol⁻¹
C. volt cm
D. ampere

Correct Answer: B
Explanation: Standard unit of molar conductance.

45. Which reaction occurs at cathode?

A. Oxidation
B. Reduction
C. Neutralization
D. Hydrolysis

Correct Answer: B
Explanation: Cathode is site of reduction.

46. Cell constant depends on:

A. Nature of electrolyte
B. Concentration
C. Geometry of cell
D. Temperature

Correct Answer: C
Explanation: It depends on distance and area of electrodes.

47. Electrochemical series is arranged according to:

A. Atomic number
B. Standard electrode potential
C. Density
D. Conductivity

Correct Answer: B
Explanation: Metals are arranged by reduction potential.

48. Which metal acts as sacrificial protection?

A. Cu
B. Fe
C. Zn
D. Ag

Correct Answer: C
Explanation: Zn corrodes in place of iron.

49. Oxidation number of electrons lost equals:

A. Charge
B. Current
C. Number of moles of electrons
D. Voltage

Correct Answer: C
Explanation: Oxidation involves loss of electrons.

50. Electrochemistry chapter mainly focuses on:

A. Thermal reactions
B. Energy changes in redox reactions
C. Gas laws
D. Nuclear reactions

Correct Answer: B
Explanation: Electrochemistry studies redox reactions and energy conversion.

✅ End of NCERT-Based MCQs on Electrochemistry – Class 12 Chemistry