Electrochemistry Mock Test – Class 12 Chemistry

1. During electrolysis of molten using inert electrodes, the products formed at the cathode and anode respectively are:

2. 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:

3. Assertion: Platinum is used in a standard hydrogen electrode even though it does not appear in the net hydrogen half-reaction.
Reason: The system needs an inert electronic conductor and catalytic surface for electron exchange.

4. Equal-concentration solutions of a strong electrolyte and a weak electrolyte are diluted by the same factor. Which observation is most reasonable?

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

6. A standard reduction potential becomes more positive as the corresponding oxidised species shows:

7. Aluminium has a strongly negative standard reduction potential, yet an aluminium surface may react slowly with an acid under some conditions. The best explanation is:

8. A learner states, “The cathode must be positive because it is always the site of reduction.” The suitable correction is:

9. In a galvanic cell, metal is converted into at electrode P, while is converted into metal at electrode Q. Assuming both electrodes are made of the reacting metals, the expected mass changes are:

10. Pure solids and pure liquids are normally omitted from because:

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

12. Two iron sheets are coated separately with zinc and nickel. Both coatings are scratched. The expected behaviour is:

13. At fixed , a graph of on the vertical axis against on the horizontal axis is a straight line with:

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

15. A hydrogen-oxygen fuel cell operates at for . The volume of oxygen consumed at STP is approximately:

16. Select the row that correctly gives the theoretical product obtained from of electrons.

17. A balanced cell reaction is multiplied by without changing temperature or standard-state conditions. The resulting changes are:

18. A graph shows the amount of an electrolysis product increasing steadily while a direct-current source is connected. At a certain time, the source is disconnected and the graph becomes horizontal. The horizontal region indicates that:

19. In the expression , the term represents:

20. 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:

21. An cell and a cell are connected in series. The silver cell operates at current efficiency, while the copper cell operates at efficiency. If of silver is deposited, the actual copper mass deposited is:

22. Select the row that consistently describes an electrolytic cell.

23. Corrected conductivity data for saturated give . If , the corresponding is:

24. 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.

25. At , the data for a cell reaction are and . Using , the electron number and standard Gibbs-energy change are approximately:

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

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

28. Besides maintaining electrical neutrality, a well-chosen salt bridge helps to:

29. 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:

30. A Daniell cell has at . Even when , the cell potential for the forward reaction is:

31. A Daniell cell deposits of copper at the cathode. The amount of zinc consumed at the anode is:

32. Two weak-electrolyte solutions are compared at the same temperature.

Which conclusion is correct?

33. In neutral, aerated moisture, a common cathodic corrosion reaction is:

34. The table gives the expected slope of an versus graph at . Select the consistent row.

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

36. Consider the following statements about tabulated standard electrode potentials.
Statement I: The listed values are normally written as reduction potentials.
Statement II: A more negative reduction potential indicates that the reduced form has a stronger tendency to undergo oxidation.
Statement III: Multiplying a half-reaction by doubles its standard electrode potential.

37. An equilibrium constant of is reported for a cell reaction at a specified temperature. The most suitable interpretation is:

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

39. The Daniell-cell reaction transfers of electrons and has . Using , its standard Gibbs-energy change is approximately:

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

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

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

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

44. A nickel-cadmium rechargeable cell uses:

45. The table gives possible changes during operation of a Daniell cell. Select the consistent row.

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

47. The current efficiency of an electrolytic process is calculated by:

48. Consider the following variables for an electrode system.
Statement I: Nature of the chemical species.
Statement II: Ionic activity or concentration.
Statement III: Temperature.
Statement IV: Gas pressure when a gas participates.
The electrode potential may depend on:

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

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