A metal M and its compound can give the following observable changes in a sequence of reactions,

$\mathrm{M}\frac{\text{ Very dilute }}{{\mathrm{HNO}}_3} \left[\begin{array}{cc}\mathrm{Colourless} \mathrm{solution}& \\ \mathrm{and} \mathrm{no} \mathrm{gas} \mathrm{is} \mathrm{enolved}& \end{array}\right]$

$\frac{\text{ Aqueous }}{\mathrm{NaOH}}⟶ \left[\begin{array}{c}\text{ White }\\ \text{ precipitate }\end{array}\right]\frac{\text{ Excess }}{\mathrm{NaOH}\left(aq\right)}\left[\begin{array}{c}\text{ Colourless }\\ \text{ solution }\end{array}\right]$

$\underset{{\mathrm{OH}}^{-}}{\overset{{\mathrm{H}}_2\mathrm{S}}{\to }}$ $\left[\begin{array}{c}\text{ White }\\ \text{ precipitate }\end{array}\right]$

The metal M can be.

Zinc nitrate is created when dil nitric acid and zinc react.

$4\mathrm{Zn}+\underset{\text{ dil }}{10{\mathrm{HNO}}_3}\to 4\mathrm{Zn}{\left({\mathrm{NO}}_3\right)}_2+{\mathrm{NH}}_4{\left({\mathrm{NO}}_3\right)}_2+3{\mathrm{H}}_2\mathrm{O}$

Sodium nitrate and a white precipitate of zinc hydroxide are created when zinc nitrate and sodium hydroxide combine.

$2\mathrm{NaOH}+\mathrm{Zn}{\left({\mathrm{NO}}_3\right)}_2\to 2{\mathrm{NaNO}}_3+\mathrm{Zn}(\mathrm{OH}{)}_2$

Sodium zincate is created when zinc hydroxide and extra sodium hydroxide react.

 $\mathrm{Zn}(\mathrm{OH}{)}_2+\underset{\text{ excess }}{2\mathrm{NaOH}}\to \underset{\text{ sodium zincate }}{{\mathrm{Na}}_2{\mathrm{ZnO}}_2}+2{\mathrm{H}}_2\mathrm{O}$

A white precipitate of zinc sulphide is created when hydrogen sulphide and sodium zincate interact.

$\underset{\text{ sodum zincate }}{{\mathrm{Na}}_2{\mathrm{ZnO}}_2}+{\mathrm{H}}_2\mathrm{S}\to \underset{\text{ white precipitate }}{\mathrm{ZnS}}+2\mathrm{NaOH}+2{\mathrm{H}}_2\mathrm{O}$