Explain why Statutes coated with white lead on long exposure to atmosphere turn black and the original colour can be restored on treatment
with H2O2.

Explain why Statutes coated with white lead on long exposure to atmosphere
turn black and the original colour can be restored on treatment
with H2O2.

Long exposure to atmosphere converts white lead into black PbS due to H2S present in the atmosphere. As a result, statues turn black. On treatment with H2O2, the black PbS get oxidized to white PbSO4 and the colour is restored. Hydrogen peroxide is just one oxygen atom different from Water.