White silver chloride turns grey when left in sunlight. What type of reaction is this, and what products are formed?
Generated by claude-sonnet-4-6 · 2026-06-26 00:53 · grounding rag
Model Answer
This is a photochemical decomposition reaction. Silver chloride decomposes in the presence of sunlight to form silver metal and chlorine gas.
$$2\text{AgCl} \xrightarrow{\text{Sunlight}} 2\text{Ag} + \text{Cl}_2$$
The silver formed gives the white AgCl its grey colour.
Source: Chapter 1, Chemical Reactions and Equations
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Explanation
- 1 mark for correctly identifying it as a photochemical decomposition reaction.
- 1 mark for the correct products: silver (Ag) and chlorine (Cl₂), ideally with the balanced equation.
- CBSE expects the word "decomposition" and the qualifier "photochemical" (sunlight-driven). Simply writing "decomposition" without the photochemical context may lose half a mark.
- The equation is a strong addition and shows clarity; always write it when you can within the word limit.