Classification Of Elements And Periodicity In Properties Ques 17
17. Which of the following electronic configuration of an atom has the lowest ionisation enthalpy?
[2007]
(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) $1 s^{2} 2 s^{2} 2 p^{5}$
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Answer:
Correct Answer: 17.(b)
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.
BETA
