Question

Which electronic configuration of an element has abnormally high difference between second and third ionisation energy?

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

Answer 1

Answer: (D)

$1s^2,2s^2 2p^6, 3s^2$

Answer 2

When the element having $1s^2, 2s^2 2p^6, 3s^2$ configuration, loss two electrons, then it acquire the electronic configuration of noble gas (Ne), so to remove third electron a large amount of energy is required and hence, its second and third ionisation energy have large difference.