Silver chloride kept in a china dish turns grey in sunlight.
Generated by claude-sonnet-4-6 · 2026-06-14 10:30 · grounding rag
Model Answer
(a) Silver chloride is white in colour when kept in the china dish.
(b) It is a photochemical decomposition reaction (decomposition by light).
$$2\text{AgCl} \xrightarrow{\text{Sunlight}} 2\text{Ag} + \text{Cl}_2$$
Silver chloride decomposes into silver (grey) and chlorine gas in the presence of sunlight.
(c) This reaction is used in black and white photography. Silver bromide (AgBr) is another chemical that can be used for the same purpose.
Source: Chapter 1, Chemical Reactions and Equations
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Explanation
- (a) is 1 mark — just state the colour: white.
- (b) is 1 mark — name the reaction type correctly (photochemical decomposition) and write the balanced equation. Examiners look for the sunlight condition written above the arrow.
- (c) is 1 mark — state the use (photography) and name one more chemical (AgBr). Both parts must be present for full credit.
- The grey colour appears because silver metal (Ag) is formed, which is grey — useful to mention briefly.