Hint:The solubility of a substance, basically a solute is the ability of the solute to get dissolved in a solvent. It is defined as the maximum amount of solute dissolved in a solvent at equilibrium.
There are different chemical reagents that are used for the detection of anions and cations in the qualitative analysis of the cations and anions. For the detection of certain transition metal cations, such as copper, cobalt, nickel, iron, etc. ammonium hydroxide is used as a reagent. For example, the blue colour of a copper solution forms a light blue colour on the ammonium hydroxide which turns Prussian blue on the addition of excess ammonium hydroxide when the light blue precipitate of cupric hydroxide dissolves to form a copper-ammonia complex.
Similarly, silver chloride that is formed as a precipitate on the addition of silver nitrate solution to a sample containing chloride, dissolves on the addition of ammonium hydroxide.
So, the answer is silver chloride.
Ammonia can act both as a base as well as a ligand. Added in small amounts, it acts as a base and reacts with the hydrogen ions from water to form the ammonium cations, while in the presence of excess of ammonia molecules, ligand exchange reactions between the metal-aqua complex and the ammonia molecules take place and the ammonia molecules take up the position of the water molecules in the metal complex. This often leads to drastic colour change as can be used for the identification of the metal ions.