Question

In which of the following options, the order of arrangement does not agree with the variation of property indicated against it?

• A. B < C < N > O (increasing first ionisation enthalpy)
• B. I < Br < Cl < F (increasing electron gain enthalpy)
• C. Li < Na < K < Rb (increasing metallic radius)
• D. $A{l}^{3+}<M{g}^{2+}<N{a}^{+}<F^{–}$ (increasing ionic size)

Answer 1

The correct option is B

I < Br < Cl < F (increasing electron gain enthalpy)

For option (B), the correct order for magnitude of electron gain enthalpy is I < Br < F < Cl.
Metallic radius increases down the group.
The ionisation energy of nitrogen is higher than the others due to its stable state that has a half filled p orbital.
Ionic size decreases for cations and increases for anions across the period.