Question
A black powder when heated with conc. $$HCl$$ gives a greenish yellow gas. The gas acts as an oxidising and a bleaching agent. When it is passed over slaked lime, a white powder is formed which is a ready source of the greenish yellow gas. The black powder and white powder respectively are
A.
$$KCl{O_3}\,{\text{and}}\,NaCl{O_3}$$
B.
$$Mn{O_2}\,{\text{and}}\,Ca{\left( {OCl} \right)_2}$$
C.
$$Mn{O_2}\,{\text{and}}\,KCl{O_3}$$
D.
$$MnC{l_4}\,{\text{and}}\,COC{l_2}$$
Answer :
$$Mn{O_2}\,{\text{and}}\,Ca{\left( {OCl} \right)_2}$$
Solution :
\[\underset{\begin{smallmatrix}
\text{Black} \\
\text{powder}
\end{smallmatrix}}{\mathop{Mn{{O}_{2}}}}\,+\underset{\text{(conc}\text{.)}}{\mathop{4HCl}}\,\to \] \[MnC{{l}_{2}}+2{{H}_{2}}O+\underset{\begin{smallmatrix}
\text{Greenish} \\
\text{yellow gas}
\end{smallmatrix}}{\mathop{C{{l}_{2}}}}\,\]
$$C{l_2} + {H_2}O \to 2HCl + \left[ O \right]$$
$${\text{Coloured matter}}\, + \left[ O \right] \to $$ $${\text{Colourless matter}}$$
\[\underset{\begin{smallmatrix}
\text{Slaked} \\
\text{lime}
\end{smallmatrix}}{\mathop{2Ca{{\left( OH \right)}_{2}}}}\,+2C{{l}_{2}}\to \] \[\underset{\begin{smallmatrix}
\text{Bleaching powder} \\
\text{(white)}
\end{smallmatrix}}{\mathop{Ca{{\left( OCl \right)}_{2}}}}\,+CaC{{l}_{2}}+2{{H}_{2}}O\]