Question

Assertion : Oxidation state of oxygen in $OF_{2}$ and $Na_{2}O$ is $+2$ and $-2$ respectively.
Reason: Oxygen is an electronegative element.

• A. If both assertion and reason are true and reason is the correct explanation of assertion.
• B. If both assertion and reason are true but reason is not the correct explanation of assertion.
• C. If assertion is true but reason is false.
• D. If both assertion and reason are false.

Answer 1

Answer: (B)

The electronegativity order of three elements involved in these compounds is $F > O > Na$. Hence in $OF _{2}$ molecule, $F$ is more electronegative than $O$, element $F$ is given oxidation state $-1$ and thus, $O$ shows $+2$ oxidation state. On the other hand, in $Na _{2} O , O$ is more electronegative than $Na$, hence, $Na$ is given $+1$ oxidation state and $O$ shows oxidation state $-2$.