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

- Statement (A) is incorrect; a mercury cell generates electrical energy via a chemical reaction, not by converting combustion energy.
- Statement (B) is incorrect; mercury cells are primary cells and are not rechargeable.
- Statement (C) is correct. The reaction in a mercury cell is:
\[ \text{Zn(Hg)} + \text{HgO}(s) → \text{ZnO}(s) + \text{Hg}(l) \] - Statement (D) is correct. Mercury cells are low-current devices frequently employed in hearing aids.

Therefore, the correct statements are (C) and (D).

Final Answer: \[ \boxed{\text{The correct answer is (C) and (D) only.}} \]