Statues coated with white lead on long exposure to atmosphere turn black and their original colour can be restored on treatment with H_2 O_2 . Why?

Statues coated with white lead on long exposure to atmosphere turn bla

1.	Statues coated with white lead on long exposure to atmosphere turn black and their original colour can be restored on treatment with H_2 O_2 . Why?
Answer» Solution :On long exposure to ATMOSPHERE, white lead gets converted to BLACK`PbS` due to action of `H_2S` present in the atmosphere. `PbO_2 + underset("From atmosphere")(H_2 S) + underset("Black")(PbS) + 2H_2 O` As a result, statues turn black. On TREATMENT of these black statues with `H_2O_2` the black PbS gets oxidised to `PbSO_4` and their COLOUR is restored. `PbS + H_2 O_2 to PbSO_4 + 4H_2 O`