Question

Study the given flow-sheet involving reaction of a metal and answer the question at the end.

A metal M and its compounds can given the following observable changes in a sequence of reaction :

$M\underset{HCl}{\overset{dilute}{\to }}\underset{A}{\left[\text{Colorless solution}\right]}\underset{NaOH}{\overset{aqueous}{\to }}\underset{B}{\left[\text{White precipitate}\right]}\underset{NaO{H}_{\left(aq\right)}}{\overset{excess}{\to }}\underset{C}{\left[\text{Colorless solution}\right]}\underset{NaO{H}_{\left(aq\right)}}{\overset{H_{2}S}{\to }}\underset{D}{\left[\text{White precipitate}\right]}$

Which of the following metal corresponds to $M$?

• A. $Mg$
• B. $Zn$
• C. $Al$
• D. $Pb$

Answer 1

Answer: (B)

$Zn$

Option (B) is correct. Metal corresponds to $Zn$.
$Zn\underset{HCl}{\stackrel{dilute}{\to }}ZnC{l}_2+HCl\left[\text{Colorless solution}\right]\underset{NaOH}{\stackrel{aqueous}{\to }}Zn(OH{)}_2\left[\text{White precipitate}\right]$

$Zn(OH{)}_2\left[\text{White precipitate}\right]\underset{NaO{H}_{(aq.)}}{\stackrel{excess}{\to }}N{a}_{2}Zn{O}_2\left[\text{Colorless solution}\right]\underset{NaO{H}_{(aq.)}}{\stackrel{H_{2}S}{\to }}ZnS\left[\text{White ppt}\right]$