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Q.
Which oxide is formed when potassium is heated in excess of oxygen?
The s-Block Elements
Solution:
Burning $K$ in excess $O _{2}$ gives the superoxide $K O _{2}$. Reaction with a large excess of metal will form the Oxide $K _{2} O$. The superoxide reacts with water to form the peroxide, $K _{2} O _{2}$, at low $T$ and the oxide at higher $T$ both with liberation of $O _{2}$.