• # question_answer 22) An aqueous solution of colourless metal sulphate M gives     a white precipitate with $N{{H}_{4}}OH$. This was soluble in excess of $N{{H}_{4}}OH$. On passing ${{H}_{2}}S$ through this solution a white ppt. is formed. The metal M in the salt is          A)  $Ca$                          B)  $Ba$C)  $Al$                           D)  $Zn$

$Z{{n}^{2+}}+2N{{H}_{4}}OH\xrightarrow{{}}\underset{White\,ppt.}{\mathop{Zn{{(OH)}_{2}}}}\,+2NH_{4}^{+}$ $Zn{{(OH)}_{2}}+2N{{H}_{4}}OH\xrightarrow{{}}\underset{\text{Soluble}}{\mathop{{{(N{{H}_{4}})}_{2}}Zn{{O}_{2}}}}\,+2{{H}_{2}}O$ ${{(N{{H}_{4}})}_{2}}Zn{{O}_{2}}+{{H}_{2}}S\xrightarrow{{}}\underset{White\,ppt.}{\mathop{ZnS}}\,+2N{{H}_{4}}OH$