Classification of Elements and Periodicity in Properties - Result Question 24
####24. Which of the following electronic configuration of an atom has the lowest ionisation enthalpy?
(a) $1 s^{2} 2 s^{2} 2 p^{3}$
(c) $1 s^{2} 2 s^{2} 2 p^{6}$
(b) $1 s^{2} 2 s^{2} 2 p^{5} 3 s^{1}$
(d) $1 s^{2} 2 s^{2} 2 p^{5}$
[2007]
Show Answer
Solution:
- (b) $1 s^{2}, 2 s^{2}, 2 p^{5}, 3 s^{1}$ is an unstable configuration with the outermost electron in $3^{\text{rd }}$ orbit. Hence, it has lowest ionisation enthalpy.
