Statement I : Acid strength increases in the order given as HF << HCl << HBr << HI

Statement II : As the size of the elements F, Cl, Br, I increases down the group, the bond strength of HF, HCl, HBr and HI decreases and so the acid strength increases.

In the light of the above statements, choose the correct answer from the options given below.

The correct answer is: Both Statement I and Statement II are true.

Explanation:

Statement I analysis:
The acidic strength of hydracids of group 17 elements (halogens) increases in the order:

$\mathrm{HF}\ll \mathrm{HCl}\ll \mathrm{HBr}\ll \mathrm{HI}$

Thus, Statement I is correct.

Statement II analysis:
As we move down group 17 from fluorine to iodine, the atomic size of the halogens increases as follows:

$F<\mathrm{Cl}<\mathrm{Br}<I$

As the size of the halogen atom increases, the overlap of orbitals between hydrogen and the halogen becomes less effective, resulting in an increase in bond length:

$H-F<H-\mathrm{Cl}<H-\mathrm{Br}<H-I$

Consequently, the bond dissociation energy (bond strength) decreases down the group in the order:

$H-F>H-\mathrm{Cl}>H-\mathrm{Br}>H-I$

Because the H-I bond is the weakest, it undergoes dissociation most easily to release hydronium ions in solution, making HI the strongest acid among them. Hence, Statement II is correct and successfully explains Statement I.