All alkali metal superoxides contain the ion `[O_(2)]`. They are

All alkali metal peroxides contain the [-O-O]^(2-) ion. They are

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

Alkali metals contain

Assertion : Superoxides of alkali metals are paramagnetic. Reason : Superoxides contain the ion O_(2)^(-) which has one unpaired electron.

Assertion : Super-oxides of alkali metals are para-magnetic. Reason : Super-oxides contain the ion O_(2)^(-) which has one unpaired electron.

Assertion : Supeoxides of alkali matels are paramagnetic. Reason : Superoxides conatain the ion O_(2)^(-) which has one unpaired electron in its anti-bonding molecule orbital.

Assertion : Superoxides of alkali metals are paramagnetic. Reason : Superoxides contain the ion O_2^- which has one unpaired electron.