Status coated with white lead on long exposure to atmosphere turn black and the original colour can be restored on treatment with H_(2)O_(2) . Why ?

Status coated with white lead on long exposure to atmosphere turn blac

1.	Status coated with white lead on long exposure to atmosphere turn black and the original colour can be restored on treatment with H_(2)O_(2) . Why ?
Answer» SOLUTION :On long exposure to atmosphere , white lead is converted into black PbS DUE to the action of `H_(2)S` PRESENT in the atmosphere . As a result , statues TURN black . `PbO_(2) + 2H_(2)S to PbS + 2H_(2)O` On treatment of these blackened statues with `H_(2)O_(2)` , black PbS gets oxidised to white `PbSO_(4)` and the colour is RESTORED. `PbS + 4H_(2)O_(2) to PbSO_(4) + 4H_(2)O`