Cathode is made of ......... in a mercury battery:

Options

A. Zn metal
B. ZnO in contact with steel
C. Steel in contact with HgO
D. Zn in contact with HgO

Answer

To determine what the cathode is made of in a mercury battery, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Mercury Battery**:
- A mercury battery is a type of primary cell, which means it is non-rechargeable. It converts chemical energy into electrical energy.

2. **Identifying Components**:
- In a mercury battery, the anode and cathode are made of specific materials. The anode is typically made of zinc.

3. **Identifying the Cathode Material**:
- The cathode in a mercury battery is made of mercuric oxide (HgO) in contact with a conductive material, which is usually carbon or steel.

4. **Analyzing the Options**:
- The options given are:
- (a) Zinc metal
- (b) ZnO in contact with steel
- (c) Steel in contact with HgO
- (d) Zinc in contact with HgO
- Among these options, the correct one that represents the cathode is (c) Steel in contact with HgO.

5. **Conclusion**:
- Therefore, the cathode in a mercury battery is made of steel in contact with mercuric oxide (HgO).

### Final Answer:
The cathode is made of **steel in contact with HgO** in a mercury battery.

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