Explain the following facts:
(a). Copper hydroxide is soluble in ammonium hydroxide but not in sodium hydeoxide.
(b). Addition of an alkali to cuprous chloride solution gives a yellow precipitate which gradually changes to a red colour.

Explanation

This is becaue `Cu^(2+)` can form many conplexes with `NH_4^(o+)` which are soluble in water.
(b). `Cu_2Cl_2+2NaOHtoCu_2Odarr+2NaCl+H_2O`
The precipitate changes colour from yellow to red due to formation of `Cu_2O`.