Q. Which one of the following has the lowest ionisation energy?
A) $1s^{2}2s^{2}2p^{6}$
B) $1s^{2}2s^{2}2p^{6}3s^{1}$
C) $1s^{2}2s^{2}2p^{5}$
D) $1s^{2}2s^{2}2p^{3}$
Explanation
(b)
$1s^{2},2s^{2},2p^{6},3s^{1}.$ It is an alkali metal; hence has least ionisation potential.
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.