Question

Statues and painting coated with white lead turn black on long exposure to atmosphere. The original color can be restored by treating them with $H_2{O}_2$ . The reason behind this is ?

• A. blackened statues get coated with $PbS$ which on reaction with $H_2{O}_2$ is oxidised to while $PbS{O}_4$
• B. $H_2{O}_2$ dissolves the coating of white lead and exposses the inner surface
• C. White lead reacts with $H_2{O}_2$ to form white $PbS{O}_4$
• D. Blackened statues get coated with lead sulphate which reacts with $H_2{O}_2$ to give $PbS$.

Answer 1

The correct option is A blackened statues get coated with $PbS$ which on reaction with $H_2{O}_2$ is oxidised to while $PbS{O}_4$

The statues and paintings coated with white lead get blackened due to formation of black PbS. It is due to action of $H_{2}S$ present in traces in atmosphere. When blackened statues are treated with $H_2{O}_2$, PbS is oxidised to $PbS{O}_4$ which is colorless or white.
$PbS+4H_2{O}_2\to PbS{O}_4+4H_{2}O$