Question

Assertion (A) : The electron gain enthalpy of oxygen is more negative than that of S.
Reason (R) : The added electron goes to smaller 2p orbitals and suffers significant repulsion
from the other electrons in this level .
Select the most appropriate answer from the options given below:
A. Both A and R are true R is the correct explanation of A
B. Both A and R are true but R is not the correct explanation of A
C. A is true but R is false
D. A is false but R is true

Answer 1

Explanation:

A. both A and R are true r is correct

Answer 2

D. A is false but R is true is the correct answer.

• As we know that when an electron is added to O or F, it goes to a smaller ($n=2$) level and suffers more repulsion than the electron in S or Cl at a larger level ($n=3$).
• Hence, the electron gain enthalpy of O or F is less than that of S or CI and is due to the smaller size of O/F the inter-electronic repulsion in compact $2$p-orbitals is much more than the repulsion in 3p-orbitals of  $S$/$CI$.
• Due to which the incoming new electron feels less attraction in O/F and more attraction in $S$/$CI$.