Why a precipitate of `Mg(OH)_2` is not formed when aqueous ammonia, `NH_4 OH` is added to a solution of `MgCl_2`?

When NH_(4)Cl is added to a solution of NH_(4)OH ,

Which compound is formed when excess of KCN is added to an aqueous solution of copper sulphate

What is the co-ordination entity formed when excess of aqueous KCN is added to an aqueous solution of copper sulphate ? Why is that no precipitate of copper sulphide is obtained when H_2 S(g) is passed through this solution ?

AgCl dissolves in NH_(4)OH due to the formation of :

What happens when KI solution is added to an aqueous solution of copper sulphate?

A colourless aqueous solution on adding water and on heating gave a white precipitate. The precipitate when reacted with NH_(4)Cl and NH_(4)OH in excess resulted in dissolution of some of the precipitate and a gelatinous precipitate is obtained. What is the hydroxide formed in aqueous solution?

Be(OH)_(2) in alkali solutions forms :

FeSO_4 solution mixed with (NH_4)_2 SO_4 solution in 1:1 molar ratio gives the test of Fe^(2+) but CuSO_4 solution mixed with aqueous ammonia in 1:4 molar ratio does not give the test Cu^(2+) ion. Explain why.

The solubility product of Mg(OH)_(2) may be written as :