Question

Which configuration represents atom having the highest second ionization energy ?

• A. $1s^2,2s^{2}2p^4$
• B. $1s^2,2s^{2}2p^6$
• C. $1s^2,2s^{2}2p^6,3s^1$
• D. $1s^2,2s^{2}2p^6,3s^2$

Answer 1

The correct option is C $1s^2,2s^{2}2p^6,3s^1$

Consider the configurations after the loss of one electron:-

A) $1s^2,2s^{2}2p^3$
B) $1s^2,2s^{2}2p^5$
C) $1s^2,2s^{2}2p^6$
D) $1s^2,2s^{2}2p^6,3s^1$

From the above, we notice that option C has attained a noble gas configuration after first ionisation. Hence it will have the highest second ionization energy compared to the rest.

Therefore option C is the right answer.