Electrochemistry Mock Test – Class 12 Chemistry

1. In the Nernst equation, the symbol represents:

2. In the combination

the ionic contributions that cancel are:

3. At , two metal ions compete for reduction at an inert cathode:


If and , which reduction is thermodynamically favoured when kinetic effects are neglected?

4. A direct-current source is connected to two inert electrodes dipped in an electrolyte. During conduction, cations move toward one electrode and anions toward the other. This observation shows that:

5. Which substance forms an electrolyte when mixed with water under ordinary conditions?

6. The conventional order used in writing a galvanic-cell notation is:

7. 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:

8. Two sparingly soluble salts P and Q give the same corrected conductivity in their saturated solutions. Their limiting molar conductivities are and , respectively. Their molar solubilities satisfy:

9. A statement says that the salt bridge carries electrons from the anode solution to the cathode solution. This description is unsuitable because:

10. Assertion: During charging of a secondary cell, electrical energy is converted into stored chemical energy.
Reason: An external power source drives the cell reaction in the direction opposite to spontaneous discharge.

11. The overall discharge reaction of a nickel-cadmium cell may be represented as:

12. An cell and a cell are connected in series, so the same charge passes through both. If of copper is deposited, the mass of silver deposited is . Given and , which reasoning is correct?

13. Match each symbol in Column I with the corresponding quantity and SI unit in Column II.

14. For an electrolyte contained between two parallel electrodes of area separated by distance , the resistance is related to resistivity by:

15. Assertion: Concentrated brine gives chlorine as the principal anodic gas under the usual inert-electrode conditions.
Reason: High chloride activity and the overvoltage associated with oxygen evolution can favour chloride oxidation.

16. A zinc concentration cell at contains concentrations of and . The correct direction and emf are approximately:

17. A student claims that conductivity and molar conductivity must always change in the same direction during dilution. The suitable correction is:

18. A lead battery is examined after prolonged discharge. Both electrodes carry a substantial layer of , and the electrolyte has become less dense. The battery is most reasonably described as:

19. At , a graph is drawn for a concentration cell with on the vertical axis and on the horizontal axis. The graph has:

20. A clean metal surface remains in dry air but begins corroding rapidly after a conducting moisture film forms. The moisture film mainly:

21. Assertion: Two reactions can have the same standard cell potential but different equilibrium constants.
Reason: The relation shows that also depends on the electron number .

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

23. In the concentration-form expression , the commonly used unit of is:

24. A conductivity cell calibrated at a fixed electrode immersion depth is later used with the electrodes only partly immersed. The original cell constant should not be assumed to remain valid because:

25. Assertion: Corrosion can occur even when the anodic and cathodic regions are parts of the same continuous metal object.
Reason: Differences in composition, stress, oxygen access, or surface condition can create local differences in electrode behaviour.

26. A concentrated aqueous solution and a very dilute aqueous solution are electrolysed using inert electrodes. The most reasonable anodic comparison is:

27. Match the dry-cell component with its principal role.

28. Under standard conditions with kinetic effects neglected, metal M displaces N and P from solutions containing and . Metal Q also displaces M from a solution containing . The relation consistent with these observations is:

29. Two unknown standard half-cells are separately connected to the standard hydrogen electrode. The observations are shown below.

The standard reduction potentials of X and Y are respectively:

30. For the Daniell-cell reaction, and at . The equilibrium constant is closest to:

31. The conductance of an electrolyte sample is related to its resistance by:

32. The conversion from the natural-logarithm form to the common-logarithm form uses the relation:

33. Combining the equilibrium condition with the Nernst equation gives:

34. Which equation represents a reduction half-reaction?

35. A fuel-cell vehicle produces water at the electrochemical stack but is not automatically environmentally impact-free because:

36. The cathodic half-reaction during electrolysis of molten is:

37. Assertion: Precipitating some from a half-cell lowers its reduction potential at fixed temperature.
Reason: Removing lowers its activity in .

38. Consider the following statements about the electrode.
Statement I: Concentration may replace activity approximately in sufficiently dilute solutions.
Statement II: The activity of pure is taken as unity.
Statement III: Decreasing lowers the reduction potential at fixed temperature.

39. Resistance measurements on a saturated salt solution give in a cell of cell constant . Pure water in the same cell has resistance . If , the salt solubility is:

40. 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:

41. Select the row that correctly compares common battery characteristics.

42. A learner extends a straight line fitted to concentrated strong-electrolyte data and treats the intercept as an exact value of . The main limitation of this method is that:

43. 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:

44. The values


and

are used to calculate . The result is:

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

46. Which surface film provides the greatest corrosion protection?

47. Assertion: Dilute is added to water before electrolysis mainly to improve electrical conductivity.
Reason: Pure water contains very few ions, whereas the added acid supplies mobile ions that can carry charge.

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

49. A reaction transfers of electrons and has . Using , its standard cell potential is:

50. A qualitative graph places molar conductivity on the vertical axis and increasing dilution, equivalent to decreasing concentration, on the horizontal axis. The expected comparison is: