Give reasons for the following :
(a) Acidic character decreases from to
because of decrease in electronegativity down the group.
(b) The three halogen atoms occupy equitorial position while the other two occupy axial positions. Since the three equatorial E-X bonds are repelled by two 'electron pairs but the two axial E-X bonds are repelled by three electron pairs, therefore axial bonds are usually longer than the equitorial bonds.
(c) It is due to high bond dissociation enthalpy of HF than , it does not release hydrogen easily hence a weaker acid than
.