Question

Which atoms should have smaller value of ${\left(IE\right)}_1$?

(a) Oxygen or sulphur
(b) Nitrogen or phosphorus

• A. (a) $S$ (b) $P$
• B. (a) $O$ (b) $P$
• C. (a) $S$ (b) $N$
• D. $Noneofthese$

Answer 1

The correct option is A (a) $S$ (b) $P$

i) In O and S, O has higher $I{E}_1$ because ionization enthalpy decreases as we descend in a group due to decrease of hold by nucleus on the outermost electron.
ii) In N and P, N has higher $I{E}_1$ because ionization enthalpy decreases as we descend in a group due to decrease of hold by nucleus on the outermost electron.