Question

General formula of the compound that will be formed, when oxygen reacts with an alkali metal, is :

• A. $M{O}_2$
• B. $M_{2}O$
• C. $M_2{O}_3$
• D. $M_3{O}_2$
• E. $MO$

Answer 1

The correct option is B $M_{2}O$

Oxygen has oxidation state of $-2\Rightarrow O^{2-}$

Alkali metal has oxidation state of $+1\Rightarrow M^{+}$

The compound formed will be $M^{+}{O}^{2-}$

On cross linking the oxidation states, the the general formula of metal oxide would be $M_{2}O$