Silver chloride turns grey on exposure to sunlight for a long duration due to:

Options

A. the formation of silver by decomposition of silver chloride.
B. sublimation of silver chloride
C. formation of chlorine gas from silver chloride
D. oxidation of silver chloride.

Explanation

**Step-by-Step Solution:**

1. **Identify the Substance**: The substance in question is silver chloride, which has the chemical formula AgCl. It is initially a white solid.

2. **Understand the Reaction**: When silver chloride is exposed to sunlight for a prolonged period, it undergoes a chemical change. This process is known as a decomposition reaction.

3. **Write the Decomposition Reaction**: The decomposition of silver chloride can be represented by the following chemical equation:
\[ 2 \text{AgCl} \xrightarrow{\text{sunlight}} 2 \text{Ag} + \text{Cl}_2 \]
This indicates that two moles of silver chloride decompose into two moles of silver (Ag) and one mole of chlorine gas (Cl₂).

4. **Observe the Color Change**: As the reaction proceeds, the white silver chloride breaks down to form silver metal, which is grey in color. This is why the initially white silver chloride turns grey upon exposure to sunlight.

5. **Conclusion**: The grey color observed is due to the formation of silver metal from the decomposition of silver chloride when it is exposed to sunlight for an extended period.

**Final Answer**: Silver chloride turns grey on exposure to sunlight for a long duration due to the decomposition of silver chloride into silver metal and chlorine gas.

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