Blue copper(II) sulfate crystals are heated in air until they become a white powder. The powder is then left to cool, and after a few days it begins to turn blue. Why does the white powder begin to turn blue?
- ACarbon dioxide in the air reacts with the powder to form copper(II) carbonate.
- BThe powder reacts with water in the air to form copper(II) hydroxide.
- CThe white copper compound is slowly oxidised.
- DWater is absorbed from the air and causes the reaction to reverse.