Assertion (A): The first ionization energy of Nitrogen is higher than that of Oxygen. Reason (R): Nitrogen has a half-filled p-orbital which is exceptionally stable. MCQ with Answer and Explanation

Assertion (A): The first ionization energy of Nitrogen is higher than that of Oxygen. Reason (R): Nitrogen has a half-filled p-orbital which is exceptionally stable.
A. Both A and R are true and R is the correct explanation of A.
B. A is true but R is false.
C. Both A and R are true but R is NOT the correct explanation of A.
D. A is false but R is true.
Answer: Option A
Solution (By JKExamLibrary)
Nitrogen (1s2 2s2 2p3) has a exactly half-filled p-subshell, which confers extra stability due to symmetry and exchange energy. Oxygen (1s2 2s2 2p4) has one paired electron in the p-orbital, leading to electron-electron repulsion, making it easier to remove. Thus, N has a higher IE than O. Both are true and R explains A.

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