Unlike dry cell, the mercury cell has a constant cell potential throughout its useful life, why?

Explanation

**Step-by-Step Text Solution:**

1. **Understanding Mercury Cell:**
- A mercury cell, often referred to as a button cell, is commonly used in devices such as hearing aids and wristwatches. It is a non-rechargeable cell that maintains a constant cell potential throughout its life.

2. **Components of the Mercury Cell:**
- The mercury cell consists of:
- **Anode:** Zinc mercury amalgam (Zn-Hg)
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