The reference calomel electrode is made from which of the following ?

Options

A. `ZnCI_(2)`
B. `CuSO_(4)`
C. `Hg_(2)CI_(2)`
D. `HgCI_(2)`

Explanation

To solve the question "The reference calomel electrode is made from which of the following?", we will analyze the options provided and identify the correct answer step by step.

### Step 1: Understand the Calomel Electrode
The calomel electrode is a type of reference electrode commonly used in electrochemistry. It consists of mercury (Hg) and mercury(I) chloride (Hg2Cl2), also known as calomel.

### Step 2: Analyze the Options
We are given four options:
- a) ZnCl2
- b) CuSO4
- c) Hg2Cl2
- d) HgCl2

### Step 3: Identify the Composition of the Calomel Electrode
The calomel electrode is specifically made from:
- **Mercury(I) chloride (Hg2Cl2)**, which is the key component of the calomel electrode.

### Step 4: Conclusion
Based on the analysis, the correct answer is option **c) Hg2Cl2**.

### Final Answer:
The reference calomel electrode is made from **Hg2Cl2**.

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