Give reasons for the following:

a) Acidic character decreases from N₂O₃ to Bi₂O_3.

b) All the P-Cl bonds in PCl₅ are not equivalent.

c) HF is a weaker acid than HCl in an aqueous solution.

a) The acidic character of oxides decreases down the group. As we know N is a non metal and metallic character increases in going down the group. Non metals form acidic oxides whereas metals form basic oxides. Thus, N₂O₃ is more acidic than Bi₂O_3.

b) PCl₅ has trigonal bipyramidal structure in which 3 equatorial P-Cl bonds are of equivalent length (202 pm) while the 2 axial bonds are longer (240 pm). It is due to the fact that axial bonds suffer more repulsion than equatorial bonds.

c) HF is a weaker acid than HCl in an aqueous solution because HF does not completely dissociate in water due to high electronegativity of F-atom. Whereas HCl dissociates completely in water due to comparatively less electronegativity of Cl than F because of which it is a stronger acid in aqueous solution.