Write balanced equations for the following conversions:

(a) $\text{Zn(SO)}$4 \xrightarrow{\text{A}} \text{Zn(OH)}2 \xrightarrow{\text{B}} \text{Na}2\text{ZnO}2

(b) $\text{Cu(SO)}$4 \xrightarrow{\text{A}} \text{Cu(OH)}2 \xrightarrow{\text{B}} \text{[Cu(NH}3)4]\text{SO}_4

(a) When sodium hydroxide solution is added dropwise to zinc sulphate, a white gelatinous ppt of zinc hydroxide is obtained.

$\underset{\text{colourless}}{{\text{ZnSO}$4}} + \underset{\text{colourless}}{2\text{NaOH}} \longrightarrow \underset{\text{white gelatinous ppt}}{\text{Zn(OH)}2} ↓ + \underset{\text{colourless}}{\text{Na}2\text{SO}4}

On adding excess of NaOH solution, the ppt dissolves and a colourless solution is obtained.

$\text{Zn(OH)}$2 + \underset{\text{excess}}{2\text{NaOH}} \longrightarrow \underset{\underset{\text{colourless}}{\text{sodium zincate}}}{\text{Na}2\text{ZnO}2} + 2\text{H}2\text{O}

(b) When ammonia solution is added dropwise to copper sulphate, a pale blue ppt of copper hydroxide is obtained.

$\underset{\text{blue}}{{\text{CuSO}$4}} + 2\text{NH}4\text{OH} \longrightarrow \underset{\text{pale blue ppt}}{\text{Cu(OH)}2} ↓ + \underset{\text{colourless in solution}}{(\text{NH}4)2\text{SO}4}

On adding excess of ammonia solution, the ppt dissolves and a deep blue solution is obtained.

$\text{Cu(OH)}$2 + (\text{NH}4)2\text{SO}4 + 2\text{NH}4\text{OH} \longrightarrow \underset{\underset{\text{copper (II) sulphate}}{\text{tetraammine}}}{[(\text{Cu(NH}3)4]\text{SO}4} + 4\text{H}_2\text{O}