Question

Assertion: Dinegative anion of oxygen $\left(O^{2-}\right)$ is quite common but dinegative anion of sulfur $\left(S^{2-}\right)$ is less common.

Reason: Covalency of oxygen is two.

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

Answer 1

Answer: (B)

If both assertion and reason are true but reason is not a correct explanation of the assertion

Usually, oxygen forms 2 bonds. So the covalency of oxygen is 2 as in $H_{2}O$.

Oxygen is the second most electronegative element after fluorine. So, it can easily gain electrons to form dinegative anion ($O^{2-}$) while sulphur is not so electronegative element as oxygen.

Therefore dinegative anion of oxygen is common because of high electron gain enthalpy.