Which of the following is correct for monoxides (normal oxides) of alkali metals ?

Options

A. They are ionic and strongly basic oxides.
B. They are pure white solids.
C. They have anti-fluorite structures.
D. All of these.

Answer

A

Explanation

They consist of `M^(+) "and" O^(2-)` ions. They react with water forming strong bases :
`M_(2)O+H_(2)O to 2MOH`
`Li_(2)O "and" Na_(2)O` are pure white solids, but surprisingly, `K_(2)O` is pale yellow, `Rb_(2)O` is bright yellow, and `Cs_(2)O` is orange.
The crystal structures of `Li_(2)O, Na_(2)O,K_(2)O " and " Rb_(2)O` are anti-fluorite structures while `Cs_(2)O` has an anti-`CdCI_(2)` layer structure.