Question

The following statements describe various properties of a Mercury cell:
(A) It converts energy of combustion into electrical energy
(B) It is rechargeable
(C) The cell reaction involved is Zn(Hg) + HgO(s) $→$ ZnO(s) + Hg(l)
(D) It is a low current device used in hearing aids

• A. (A), (B) and (D) only
• B. (A) and (C) only
• C. (A), (B), (C) and (D)
• D. (C) and (D) only

Hint:

Mercury cells are primary cells used in small devices that require low current.

Answer 1

The Correct Option is D

To determine the correct statements regarding the properties of a Mercury cell, let's analyze each given option:

1. Statement (A): "It converts energy of combustion into electrical energy"
   A Mercury cell converts chemical energy into electrical energy, not energy from combustion. Therefore, this statement is incorrect.
2. Statement (B): "It is rechargeable"
   Mercury cells are typically primary cells, meaning they are not rechargeable. Therefore, this statement is incorrect.
3. Statement (C): "The cell reaction involved is Zn(Hg) + HgO(s) → ZnO(s) + Hg(l)"
   This statement accurately describes the cell reaction in a Mercury cell, where zinc amalgam (Zn(Hg)) reacts with mercuric oxide (HgO) to produce zinc oxide (ZnO) and liquid mercury (Hg). Therefore, this statement is correct.
4. Statement (D): "It is a low current device used in hearing aids"
   Mercury cells are known for providing a stable voltage and are used in low-current devices such as hearing aids and watches. Therefore, this statement is correct.

After evaluating all the statements, we find that the correct description of properties for a Mercury cell corresponds to statements (C) and (D). Thus, the correct answer is:

(C) and (D) only