Question

Which of the following configurations corresponds to element of highest ionisation energy?

• A. $1s^2,2s^1$
• B. $1s^2,2s^2,2p^3$
• C. $1s^2,2s^2,2p^2$
• D. $1s^2,2s^2,2p^6,3s^1$

Answer 1

Answer: (B)

$1s^2,2s^2,2p^3$

Comparing to other electronic configuration, half filled orbitals are highly stable.

So, $1s^{2}2s^{2}2p^3$ has half-filled orbital in it valence p-shell, so it is more stable.