Question

Statues and paintings coated with lead turn black on long exposure to atmosphere. The original colour can be restored by treating them with $H_{2}O$. The reason behing this is.

• A. Blackened statues get coated with pbs which on reaction with $H_{2}O_{2}$is oxidised to white $pbSO_{4}$
• B. $H_{2}O_{2}$dissolves the coating of white lead and exposes the inner surface.
• C. White lead reacts with $H_{2}O$to form white $pbSO_{4}$
• D. Blackened statues get coated with lead sulphate which reacts with $H_{2}O_{2}$to give Pbs.

Answer 1

Answer: (A)

Blackened statues get coated with pbs which on reaction with $H_{2}O_{2}$is oxidised to white $pbSO_{4}$

Answer 2

: The statues and paintings coated with white lead get blackened due to action of $H_{2}O$present in traces in atmosphere. When these are treated with $H_{2}O$PbS is

Oxidised to $PbSO_{4}$which is colourless or white

$\underset{black}{PbS} + 4H_{2}O_{2} \rightarrow \underset{white}{PbSO_{4}} + 4H_{2}O$