Statement-1 : $N{H}_{4}Cl$ and  $N{H}_{4}OH$ can be used to separate a mixture containing  $C{r}^{3+},N{i}^{+2}$
Statement-2 : $N{H}_{4}Cl$  increases $\left(N{H_4}^{+}\right)$  in $N{H}_{4}OH$  thus increases ionic product of chromium $\left(III\right)$  hydroxide and it exceeds solubility product of $Cr{\left(OH\right)}_3$ and $Cr{\left(OH\right)}_3$ gets precipitated. 

Statement-1 is False, Statement-2 is True.

Statement-1 is True, Statement-2 is False 

Statement -1 is True, Statement-2 is True; Statement-2 is a NOT correct explanation for Statement-1.

Statement -1 is True, Statement-2 is True; Statement-2 is a correct explanation for Statement-1.