Electrochemistry Mock Test – Class 12 Chemistry

1. For a fixed electrolyte and fixed electrode separation, conductance is plotted against electrode area . The ideal graph is:

2. The names anode and cathode are assigned primarily according to:

3. Both electrodes of a lead storage cell become coated with during discharge, yet they do not undergo identical half-reactions because:

4. A suitable experimental arrangement for accurate conductivity measurement contains:

5. A coastal installation contains an underground steel pipeline and an exposed steel railing. The pipeline cannot be inspected frequently, while the railing can be repainted during maintenance. Which protection plan is most appropriate?

6. The reduction half-reaction has the reaction quotient:

7. A half-cell is most appropriately described as:

8. Assertion: A direct-current source is required to maintain an electrolytic reaction.
Reason: The source supplies energy and controls electron removal from the anode and electron delivery to the cathode.

9. In an electrochemical cell, an electrode is best described as:

10. At , the Nernst equation written with common logarithms is:

11. In an SHE-coupled cell, hydrogen gas is oxidised according to , while an unknown species is reduced at the other electrode. The consistent conclusion is:

12. The Faraday constant represents:

13. Assertion: A cell containing two suitable electrode reactions may fail to deliver a sustained current if its internal ionic path is interrupted.
Reason: Continued electron transfer without compensating ion movement causes charge to accumulate in the half-cells.

14. Arrange the principal stages of rust formation in the most reasonable order.
Stage P: combines with to form .
Stage Q: Iron is oxidised to .
Stage R: Hydrated iron(III) oxide products develop.
Stage S: Oxygen is reduced to produce .

15. Assertion: Charging a lead storage cell increases the sulphuric-acid concentration.
Reason: The charging process reverses the discharge reaction and converts back into , , and .

16. A weak electrolyte becomes more highly ionised when diluted, yet its conductivity still generally decreases. The best explanation is that:

17. The balanced anodic half-reaction for acidified-water electrolysis is:

18. Molar conductivity is best described as:

19. The important distinction between electrolysis of a molten electrolyte and its aqueous solution is that:

20. A salt bridge is required for a cell containing in one half-cell and in the other. The most suitable bridge electrolyte among the following is:

21. Which statement correctly distinguishes limiting molar conductivity from conductivity at infinite dilution?

22. Two concentration cells use the same electrodes. Cell P has a concentration ratio of , while Cell Q has a concentration ratio of . At the same temperature:

23. Assertion: The molar conductivity of a strong electrolyte increases only moderately on dilution.
Reason: A strong electrolyte is already largely dissociated, so dilution mainly reduces interionic interactions rather than producing many additional ions.

24. Faraday’s first law of electrolysis states that, when other conditions are fixed, the mass of substance produced at an electrode is directly proportional to:

25. Assertion: The anode of a spontaneously operating galvanic cell is negative.
Reason: Oxidation at the anode supplies electrons to the external circuit.

26. In the Nernst equation, the symbol represents:

27. A conductivity cell is calibrated with a standard solution having conductivity and resistance . An unknown solution then gives resistance in the unchanged cell. Which pair is correct?

28. Match each cell component in Column I with its primary function in Column II.

29. For a two-electron reaction at , . Its standard cell potential is:

30. A graph records electrode mass against time during steady Daniell-cell operation. Line P decreases with time, while line Q increases with time. The correct assignment is:

31. During electrolysis of molten , of sodium is produced. The amount of chlorine gas formed simultaneously is:

32. The nature of the electrode can change the electrolysis product because:

33. When the complete Daniell-cell reaction is reversed while the physical state of the system is unchanged:

34. Assertion: A sacrificial anode must be replaced periodically.
Reason: It protects the main structure by undergoing preferential oxidation and is gradually consumed.

35. A cell has emf and internal resistance . When it supplies a current of , its terminal voltage is:

36. Eight lead-acid cells, each of emf , are connected in series. Seven cells have the same orientation, while one cell is accidentally reversed. The net emf is:

37. If the concentration of a strong electrolyte is increased from to , the term in the relation becomes:

38. Two standard half-cells have and . When they form a spontaneous galvanic cell:

39. Select the row that describes the expected local changes during concentrated-brine electrolysis with inert electrodes.

40. The external wire of a galvanic cell is suddenly disconnected while the internal ionic connection remains in place. The sustained cell current stops because:

41. Select the row that consistently describes electrolysis of aqueous with inert electrodes.

42. Given


and

the limiting molar conductivity of is:

43. The cell constant of a conductivity cell is:

44. In an industrial brine electrolyser, a membrane or separator is mainly used to:

45. A conventional Daniell cell is constructed using:

46. An electrolyte shows resistance in a cell having electrode separation and electrode area . Its conductivity is:

47. The cathodic reaction during electrolysis of aqueous with inert electrodes is:

48. A water droplet rests on an iron surface. The centre beneath the droplet is relatively oxygen-poor, while the edge is oxygen-rich. The most likely assignment is:

49. Select the row that consistently describes a spontaneously operating galvanic cell.

50. The general Nernst equation for a cell reaction is: