Which one of the alkali metals, forms only, the normal oxide, M₂O on heating in air

Options

(a) Rb
(b) K
(c) Li
(d) Na

Correct Answer:

Li

Explanation:

When alkali metals heated in atmosphere of oxygen, the alkali metals ignite and form oxides.On combustion, Li forms Li₂O; sodium gives the peroxide Na₂O₂ and potassium and rubidium gives superoxide(MO₂).