Question

Assertion :Nitrogen has higher ionization energy than that of oxygen. Reason: Nitrogen has smaller atomic size than that of oxygen.

• A. Both Assertion and Reason are correct and Reason is the correct explanation of Assertion
• B. Both Assertion and Reason are correct, but Reason is not the correct explanation of assertion
• C. Assertion is correct but Reason is incorrect
• D. Assertion is incorrect but Reason is correct

Answer 1

The correct option is C Assertion is correct but Reason is incorrect

Electronic configuration of $N$(atomic no. 7) is: $1s^{2}2s^{2}2p^3$
Electronic configuration of $O$(atomic no. 8) is: $1s^{2}2s^{2}2p^4$
Now Ionisation energy(I.E) is the energy required to remove an electron from the valence shell of an atom.As seen in the configuration,$N$ atom has stable half filled valence p-orbital ,therefore large amount of energy is required to remove the valence electron from $N$ atom.Therefore I.E of $N$ is higher than that of $O.$