Assertion:For the elements O or F,the electron gain enthalpy is less negative than that of the succeeding element.
Reason:Electron gain enthalpy becomes less negative as we go down a group.

Options

A. If both assertion and reason is the correct explanation of assertion.
B. If both assertion and reason is the correct explanation of assertion.
C. If both assertion and reason is the correct explanation of assertion.
D. If both assertion and reason is the correct explanation of assertion.

Answer

B

Explanation

Generally,electron gain enthalpy becomes less negative(decreases)as we go down the group because size of the atom increases and the added electron will be father from the nucleus.But in case of O or F,the added electron goes to the smaller quantum level i.e.,n=2 and suffers significant repulsion from other electrons presents in this level.