Question

hf is weakest acid and hi is strongest acid ?

Answer 1

Iodine(I) has a bigger atomic radius than Fluorine(F).Due to its greater size, the distance between the valence electron and the nucleus is greater than Fluorine.

Due to the larger distance, when is makes a bond, the distance between H+ and the nucleus of I is greater as compared to F and H+.

Due to larger bond length, bond strength is low and, thus, it is easy to break.And therefore more reactive.

While in F and H+,the bond length is significantly less and thus strengthening the bond.Therefore the bond is difficult to break.