In presence of sunshine, white silver chloride turns grey. This results from the photochemical breakdown of______ into chlorine and silver.

In presence of sunshine, white silver chloride turns grey. This is because light causes silver chloride to break down into silver and chlorine. This is a type of decomposition reaction. 

Hence, In presence of sunshine, white silver chloride turns grey. This results from the photochemical breakdown of silver chloride into chlorine and silver.