Question Detail
Question
The correct order for first ionization energies among Be, B, N, and O is __________ < __________ < __________ < __________.
Correct Answer
Option B is the correct answer.
Detailed Explanation
General trend increases left to right, but with exceptions: Be (2s² full) has higher IE than B (2s²2p¹). N (2s²2p³ half-full) has higher IE than O (2s²2p⁴). So order: B (lowest) < Be < O < N (highest).
Hint
Remember the exceptions at full (Be) and half-full (N) subshells.