Question

Among the following, the element of higher first ionisation enthalpy is:

• A. $C$
• B. $F$
• C. $Be$
• D. $N$
• E. $Ne$

Answer 1

Answer: (E)

$Ne$

The electronic configuration of the given elements is:

${}_{6}C=1s^2,2s^2,2p^2$

${}_{9}F=1s^2,2s^2,2p^5$

${}_{4}Be=1s^2,2s^2$

${}_{7}N=1s^2,2s^2,2p^3$

${}_{10}Ne=1s^2,2s^2,2p^6$

Thus, $Ne$ has the highest ionisation enthalpy because of its completely filled configuration and high effective nuclear charge.