Electrochemistry Mock Test – Class 12 Chemistry

1. Consider the following precautions during conductivity measurement.
Statement I: The cell should be rinsed with the solution being measured before the final reading.
Statement II: Air bubbles should not remain attached to the electrode surfaces.
Statement III: The temperature should be kept constant during comparison of solutions.

2. In the expression , the term represents:

3. At equilibrium in a reversible electrochemical cell, the cell potential is:

4. When the ion activities in the two half-cells of an ideal concentration cell become equal:

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

6. A copper vessel is proposed for storing . Given and , the proposal is unsuitable because:

7. A set of limiting-conductivity measurements shows that replacing by increases by the same amount in and . This observation supports Kohlrausch’s law because:

8. A cell at has , , and . Its cell potential is:

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

10. The overall reaction for electrolysis of concentrated aqueous sodium chloride is:

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

12. Consider the following statements about the non-standard Daniell cell.
Statement I: The electron number used in the Nernst equation is .
Statement II: Activities of pure and are omitted from .
Statement III: Increasing at fixed raises .

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

14. Four solutions of equal concentration are measured at the same temperature.

The most reasonable conductivity order is:

15. Which combination can be used to obtain from strong-electrolyte limiting conductivities?

16. Rust is commonly represented approximately as ______.

17. A nickel-cadmium rechargeable cell uses:

18. In the combination

the ionic contributions that cancel are:

19. Two circuits contain identical lamps and equal applied potential differences. Circuit P uses a metal wire as the conducting path, whereas circuit Q uses an electrolyte between inert electrodes. After prolonged operation, chemical products are detected near the electrodes only in Q. This difference arises because:

20. When of zinc is oxidised completely in a Daniell cell, the amount of electrons transferred is:

21. Selective discharge during electrolysis refers to:

22. When the iron-oxidation reaction is combined with oxygen reduction in neutral water, the initial electrochemical stage can be represented by:

23. Assertion: The approximation becomes less reliable as a weak electrolyte is extensively diluted.
Reason: The degree of dissociation increases on dilution and may no longer be negligibly small.

24. In an ideal electrolytic cell with copper electrodes, the cathode gains of copper. The expected anode-mass change and bulk -concentration change are:

25. The notation written for a hydrogen electrode contains , , and . A single vertical line must be placed wherever:

26. Select the row in which the proposed strong-electrolyte combination does not produce the stated weak electrolyte after ionic cancellation.

27. Overvoltage is the ______ required beyond the thermodynamic equilibrium potential to sustain an electrode process at an appreciable rate.

28. The SI unit of molar conductivity is:

29. In the differential-aeration cell formed beneath a water droplet on iron, electrons move:

30. Hydrogen and chlorine produced during brine electrolysis are collected separately under identical temperature and pressure. If their combined volume is , their individual volumes are:

31. The same solution has conductivity . Cell P has cell constant , while Cell Q has cell constant . Their measured resistances are:

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

33. Adding the balanced electrode reactions for electrolysis of molten gives:

34. A current of deposits of silver from . Given and , the required time is:

35. The balanced anodic half-reaction for molten sodium chloride is:

36. Assertion: The overall cell reaction must be balanced before the Nernst equation is applied.
Reason: The balanced coefficients determine both the reaction-quotient powers and the electron number .

37. The slope of a versus graph for a strong electrolyte is:

38. An iron sheet is electrically connected to a copper strip and exposed to moist air. If a galvanic couple forms, the most likely result is:

39. Painting and greasing protect iron primarily by:

40. In a redox process, oxidation and reduction must occur together because:

41. Identical clean iron nails are kept under the following conditions for the same time.

Which order of expected rusting from greatest to least is most reasonable?

42. Corrosion of a metal is best understood as:

43. Which comparison between a common dry cell and a mercury cell is correct?

44. Two electrodes at contain concentrations of and . The potential of the more concentrated electrode exceeds that of the dilute electrode by:

45. Assertion: At infinite dilution, the ions of an electrolyte contribute approximately independently to its molar conductivity.
Reason: The average separation between ions becomes very large, so interionic interactions become negligible.

46. A calculation for a cell at uses . The main error is that:

47. The table lists metal-displacement situations under standard conditions. Select the row with the consistent prediction.

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

49. 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:

50. The anodic half-reaction during discharge of a lead storage cell is: