Question

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. $$Zn$$  
Answer :   $$Zn$$
Solution :
$$\eqalign{ & Z{n^{2 + }} + 2N{H_4}OH \to \mathop {Zn{{\left( {OH} \right)}_2}}\limits_{{\text{White ppt}}.} + 2NH_4^ + \cr & Zn{\left( {OH} \right)_2} + 2N{H_4}OH \to \mathop {{{\left( {N{H_4}} \right)}_2}}\limits_{{\text{Soluble}}} Zn{O_2} + 2{H_2}O \cr & {\left( {N{H_4}} \right)_2}Zn{O_2} + {H_2}S \to \mathop {ZnS}\limits_{{\text{White ppt}}{\text{.}}} + 2N{H_4}OH \cr} $$

Releted MCQ Question on
Inorganic Chemistry >> Qualitative Analysis

Releted Question 1

The ion that cannot be precipitated by both $$HCl\,{\text{and}}\,{H_2}S$$    is

A. $$P{b^{2 + }}$$
B. $$C{u^ + }$$
C. $$A{g^ + }$$
D. $$S{n^{2 + }}$$
Releted Question 2

Which one among the following pairs of ions cannot be separated by $${H_2}S$$  in dilute hydrochloric acid?

A. $$B{i^{3 + }},S{n^{4 + }}$$
B. $$A{l^{3 + }},H{g^{2 + }}$$
C. $$Z{n^{2 + }},C{u^{2 + }}$$
D. $$N{i^{2 + }},C{u^{2 + }}$$
Releted Question 3

An aqueous solution contains $$H{g^{2 + }},Hg_2^{2 + },P{b^{2 + }}\,{\text{and}}\,C{d^{2 + }}.$$
The addition of $$HCl\left( {6N} \right)$$   will precipitate:

A. $$H{g_2}C{l_2}\,{\text{only}}$$
B. $$PbC{l_2}\,{\text{only}}$$
C. $$PbC{l_2}\,{\text{and}}\,H{g_2}C{l_2}$$
D. $$PbC{l_2}\,{\text{and}}\,HgC{l_2}$$
Releted Question 4

Identify the correct order of solubility of $$N{a_2}S,\,CuS\,{\text{and}}\,ZnS$$     in aqueous medium

A. $$CuS > ZnS > N{a_2}S$$
B. $$ZnS > N{a_2}S > CuS$$
C. $$N{a_2}S > CuS > ZnS$$
D. $$N{a_2}S > ZnS > CuS$$

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