Electrochemistry Mock Test – Class 12 Chemistry

1. 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:

2. Acidic conditions can accelerate corrosion of many active metals because ions may:

3. A current of passes through acidified water for . Taking , the volume of produced at standard temperature and pressure is:

4. A weak electrolyte has relatively low molar conductivity at moderate concentration because:

5. Assertion: A weak electrolyte can show a large increase in molar conductivity even though its conductivity decreases on dilution.
Reason: Dilution lowers the number of ions per unit volume but increases ionisation and the conducting contribution per mole.

6. Consider the following statements about molten electrolysis.
Statement I: migrates toward the cathode and undergoes reduction.
Statement II: migrates toward the anode and undergoes oxidation.
Statement III: Water competes with for reduction at the cathode.

7. 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:

8. Molar conductivity is best described as:

9. A learner claims that electrons in a galvanic cell move from the positive cathode to the negative anode because electrons are attracted toward a negative electrode. The suitable correction is:

10. Assertion: Electrochemistry includes both battery operation and electrolysis.
Reason: Oxidation occurs at the anode in every electrochemical cell.

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

12. The principal role of an electrolyte in an electrochemical cell is to:

13. Complete the conductivity relation:

14. Consider the following statements about multiplying a balanced electrochemical reaction by an integer .
Statement I: is multiplied by .
Statement II: is multiplied by .
Statement III: remains unchanged.
Statement IV: becomes .

15. 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.

16. For two electrolytes and , the relation

is equal to:

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

18. During electrolysis of concentrated brine, of is produced. According to the overall reaction, the amount of formed is:

19. A weak-electrolyte solution has conductivity at . After dilution to , its conductivity becomes . Its molar conductivity:

20. Conductivity data give the degree of dissociation of a weak electrolyte through:

21. Use the arrangement described below. A platinised platinum strip is in contact with and an acidic solution under standard conditions. The platinum surface is connected to an external circuit. The component that acts as the redox couple is:

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

23. A reversible cell transfers of electrons per mole of reaction and operates at . Using , the maximum non-expansion electrical work obtainable per mole of reaction is:

24. A solution has true resistance in a calibrated cell of cell constant . Because of an attached bubble, the measured resistance becomes . The conductivity calculated from the faulty reading is:

25. The cathodic discharge reaction in a lead storage cell is:

26. Which surface film provides the greatest corrosion protection?

27. Painting and greasing protect iron primarily by:

28. Aqueous is electrolysed using inert platinum electrodes. The principal products are:

29. A suitable notation for a standard hydrogen half-cell written with the platinum conductor at the outer end 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. Select the row that describes the expected local changes during concentrated-brine electrolysis with inert electrodes.

32. A simplified equation for further oxidation of iron(II) hydroxide during rust formation is:

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

34. At a cathodic region on rusting iron exposed to neutral aerated water, the principal reaction is:

35. 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:

36. In a galvanic cell, oxidation produces additional positive ions in half-cell P, while reduction removes positive ions from half-cell Q. The salt-bridge ions that should migrate toward P and Q respectively are:

37. Using and , the Faraday constant is approximately:

38. Two electrolytes give the following observations when diluted by the same factor.

The most reasonable classification is:

39. The same electrolyte is examined at infinite dilution in two solvents at the same temperature. Solvent P is much more viscous and solvates the ions more strongly than Solvent Q. The most reasonable prediction is:

40. The cathodic reaction in an alkaline hydrogen-oxygen fuel cell is:

41. Assertion: A mercury cell provides a nearly constant potential of about during much of its useful discharge.
Reason: Its overall discharge reaction does not involve a substantial change in the concentration of dissolved ionic species.

42. Which limiting pair is consistent with ?

43. During discharge of a lead storage cell, the electrode materials and electrolyte are:

44. The Daniell cell is classified as a galvanic cell because it:

45. Consider the following statements about electrolysis of concentrated brine.
Statement I: Water is reduced at the cathode.
Statement II: Chloride ions are oxidised at the anode.
Statement III: Sodium ions remain mainly in solution and accompany the hydroxide ions formed.

46. An aqueous solution contains equal activities of , , and . Their standard reduction potentials are , , and , respectively. At an inert cathode, neglecting kinetic complications, the species discharged first is:

47. In an aqueous solution containing a halide ion, increasing the halide concentration may favour halogen formation at the anode because:

48. For a strong electrolyte, molar conductivity generally increases on dilution primarily because:

49. 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.

50. The following reactions are considered at .

The order of their standard cell potentials is: