Question

The element with the highest first ionization energy among the following is:

• A. B
• B. C
• C. N
• D. O

Hint:

Remember the anomaly caused by the half filled 2p subshell of nitrogen.

Answer 1

The Correct Option is C

N places one e- in each of 3 2p orbitals, symmetric, stable. O must pair up a 4th e-, causing repulsion that makes removal easier despite higher nuclear charge.

\[\boxed{N}\]