Electrochemistry Mock Test – Class 12 Chemistry

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

2. Use the four arrangements below.
Case P: in and in , with an external wire and an ionic connection.
Case Q: in and in , with neither connection.
Case R: Two electrodes in identical solutions.
Case S: and placed in separate dry, empty beakers.
The arrangement representing a complete Daniell cell is:

3. A graph shows conductance on the vertical axis and temperature on the horizontal axis. Curve P slopes downward for a metal, while curve Q slopes upward for an electrolyte solution over the same moderate temperature range. The best interpretation is:

4. A one-electron reaction at has . Its equilibrium constant is:

5. An initially blue aqueous solution is electrolysed with inert electrodes. After some time, the cathode is coated with a reddish-brown solid, bubbles appear at the anode, the blue colour becomes paler, and the pH falls. The best explanation is:

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

7. Assertion: Standard electrode potentials alone may not predict the observed electrolysis product correctly.
Reason: Concentration, electrode material, and overvoltage can alter the relative ease of competing electrode processes.

8. Select the row that consistently relates cell potential, Gibbs-energy change, and reaction tendency.

9. Equal-concentration aqueous solutions of and are compared at the same temperature. The solution normally has higher conductivity because:

10. A nickel-cadmium rechargeable cell uses:

11. The thermodynamic relation connecting the Gibbs-energy change of a reversible cell reaction with its cell potential is:

12. Assertion: A concentration cell tends to reduce the concentration difference between its two half-cells.
Reason: Oxidation occurs in the dilute half-cell, while reduction occurs in the concentrated half-cell.

13. The spontaneous tendency responsible for Daniell-cell operation is represented by:

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

15. At a specified temperature, and . The limiting molar conductivity of is:

16. In acidic representation, the cathodic half-reaction during electrolysis of acidified water is:

17. An ideal battery has a capacity of . If it supplies a constant current of , the expected operating time is:

18. Conductivity data for a sparingly soluble salt give its molar solubility through:

19. The correct pair of electrode reactions for electrolysis of aqueous using copper electrodes is:

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

21. Two standard cells use the half-cell as the cathode. Cell P uses as the anode, while Cell Q uses as the anode. Given , , and , the difference is:

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

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

24. 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.

25. 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.

26. A rechargeable battery is required for repeated cycling in portable equipment. Compared with a lead storage battery, a nickel-cadmium cell is associated with:

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

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

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

30. A weak monoprotic acid has concentration and degree of dissociation . Its concentration-form dissociation constant is:

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

32. During discharge of a mercury cell, the electrode materials are correctly identified as:

33. A calculation gives for a weak electrolyte at finite concentration. The safest conclusion is that:

34. 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:

35. A silver-plating cell deposits of silver in with a current efficiency of . Given and , the current supplied is approximately:

36. The valid SI-unit combination is:

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


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

38. Use the standard reduction potentials in the table.

The strongest oxidising agent and strongest reducing agent among the listed species are respectively:

39. In the reaction , the reducing agent is:

40. For a strong electrolyte, at , while at . Assuming linear behaviour, is:

41. A student claims that a singly charged cation must always be discharged before a doubly charged cation. The most appropriate correction is:

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

44. Select the correctly written expression for of .

45. Consider the following statements.
Statement I: Oxidation always occurs at the anode.
Statement II: Reduction always occurs at the cathode.
Statement III: The anode must be negative in every electrochemical cell.

46. Calibration of a conductivity cell with standard is preferred over calculating only from ruler measurements because:

47. A student says, “Conductivity must change whenever a solution is transferred to a cell of different dimensions because its measured conductance changes.” The suitable correction is:

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

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

50. An electrode has . At , when , its reduction potential is approximately: