Which gas is released during the photodecomposition of silver chloride?

The correct option is Chlorine.

Explanation

The reaction described is an example of photodecomposition (or photolysis), a specific type of decomposition reaction where a chemical compound breaks down into simpler substances upon exposure to light energy.

Detailed Analysis:

• Reactant: Silver chloride (AgCl) is a white solid substance.
• Process: When placed in sunlight, silver chloride absorbs light energy and decomposes.
• Products: The reaction yields solid silver (Ag), which turns the substance grey, and releases chlorine gas (Cl₂).
• The chemical equation representing this change is:
  2AgCl(s) $\xrightarrow{\text{Sunlight}}$ 2Ag(s) + Cl₂(g)

Key Takeaway:

Photodecomposition of silver halides (such as silver chloride and silver bromide) releases halogen gases (chlorine or bromine) and produces silver metal. This chemical property is the fundamental principle behind black and white photography.