The cloudy solution in a silver nitrate test is caused by the formation of silver chloride (AgCl).

Here's why:

* Silver nitrate (AgNO3) is a soluble compound, meaning it dissolves in water.

* When silver nitrate reacts with a solution containing chloride ions (Cl-), a precipitation reaction occurs.

* Silver chloride (AgCl) is a white, insoluble solid that forms a cloudy precipitate in the solution.

The reaction can be represented as:

AgNO3 (aq) + Cl- (aq) → AgCl (s) + NO3- (aq)

This reaction is often used to test for the presence of chloride ions in a sample, as the formation of the cloudy precipitate is a strong indicator of their presence.