White silver chloride turns grey in sunlight. What type of reaction is this?
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → Decomposition
In sunlight silver chloride breaks up into its elements: 2AgCl → 2Ag + Cl2. The grey colour is the finely divided silver left behind, and because light supplies the energy the change is called a photolytic decomposition.
It is the reaction behind black-and-white photography. A single compound splitting into simpler substances is decomposition, not combination, oxidation or displacement.