A white precipitate will be formed if we add ammonia solution to:

When ammonia solution is added to aluminum chloride (AlCl3), a white precipitate of aluminum hydroxide (Al(OH)3) is formed. This reaction can be represented as: AlCl3 + 3NH3 + 3H2O → Al(OH)3 (white precipitate) + 3NH4Cl. None of the other solutions (Mg(NO3)2, KNO3, Ba(NO3)2) would produce a white precipitate with ammonia solution.