Lithium forms monoxide only when heated in oxygen. Sodium forms monoxide and peroxide in excess of oxygen. Other alkali metals form superoxide with oxygen i.e `MO_(2)`. The abnormal behaviour of lithium is due to small size. The larger size of nearer alkali metals also decides the role in formation of superoxides. The three ions are related to each other as follows
`O^(2-) overset(1/2O_(2))rarrunderset(O_(2^(2-)))overset(O_(2))rarrunderset("superoxide ion")2O_(2)`
Lithium does not form stable peroxide because

Options

A. `Na_(2)O_(2)`
B. `KO_(2)`
C. `Na_(2)O`
D. `Cs_(2)O_(2)`

Answer

B

Explanation

`2KO_(2)+2H_(2)Orarr2KOH+H_(2)O_(2)+O_(2)`