Question

In the presence of $S{O}_3^{2-}$ and $S^{2-}$ in a mixture, on adding $dil.H_{2}S{O}_4$, one notices :

• A. $S{O}_2$ and $H_{2}S$ are not formed
• B. $S{O}_2$ and $H_{2}S$ formed during change undergoes a redox change forming colloidal sulphur and thus, no smell
• C. a smell of burning sulphur
• D. a smell of rotten egg

Answer 1

Answer: (B)

$S{O}_2$ and $H_{2}S$ formed during change undergoes a redox change forming colloidal sulphur and thus, no smell

The reaction is given below:
$S{O}_3^{-2}+S^{-2}\stackrel{H^{+}}{\to }S{O}_2+H_{2}S\to H_{2}O+3S$
$S{O}_2$ and $H_{2}S$ formed during change undergoes a redox change forming colloidal sulphur and thus, no smell is observed.