Q28 / 160 · AP EAMCET 2023 (16 May Shift 2) · Chemistry
Which of the following are not in accordance with the property mentioned against them?
I. $\mathrm{F}_2>\mathrm{Cl}_2>\mathrm{Br}_2>\mathrm{I}_2$ : Oxidising power
II. $\mathrm{MI}>\mathrm{MBr}>\mathrm{MCl}>\mathrm{MF}$ : Ionic character of metal halide
III. $\mathrm{F}_2>\mathrm{Cl}_2>\mathrm{Br}_2>\mathrm{I}_2$ : Bond dissociation enthalpy
IV. $\mathrm{HI} < \mathrm{HBr} < \mathrm{HCl} < \mathrm{HF}$ : Hydrogen-halogen bond strength
- AI \& III only
- Correct answerBII \& III only
- CI \& IV only
- DII \& IV only
Solution
Ionic character of metal halide :-
$\mathrm{M}-\mathrm{F}>\mathrm{M}-\mathrm{Cl}>\mathrm{M}-\mathrm{Br}>\mathrm{M}-\mathrm{I}$
This is due to low polarizability of fluorine due to very small size which gives more ionic character.
Thus, II is incorrect.
Order of bond dissociation enthalpy :-
$\mathrm{Cl}_2>\mathrm{Br}_2>\mathrm{F}_2>\mathrm{I}_2$
This is due to very small size and $\mathrm{F}-\mathrm{F}$ bond length that causes repulsion between the atoms and possible multiple bonds between $\mathrm{Cl}_2, \mathrm{Br}_2$ and $\mathrm{I}_2$ due to availability of $\mathrm{d}$ orbitals.
Thus, III is incorrect.
Hence, the correct answer is option: 'B'.