Name the electrolyte used in fuel cell and mercury cell.

Explanation

To answer the question regarding the electrolytes used in fuel cells and mercury cells, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Fuel Cells:**
- Fuel cells are devices that convert chemical energy from fuels into electrical energy through electrochemical reactions.
- The electrolyte in a fuel cell is crucial as it allows the movement of ions between the anode and cathode, facilitating the generation of electricity.

...