The basic nature of the hydroxides of group 13 (Gr. III B) decreases progressively down the group.

Pick out the isoelectronic structures from the following
I. $$CH_3^+$$
II. $$H_3O^+$$
III. $$NH_3$$
IV. $$CH_3^-$$

The dipole moment of KCl is 3.336 $$\times$$ 10^-29 Coulomb meters which indicates that it is a highly polar molecule. The interatomic distance between K⁺ and Cl^- in this molecule is 2.6 $$\times$$ 10^-10. Calculate the dipole moment of KCl molecule if there were opposite charges of one fundamental unit located at each nucleus. Calculate the percentage ionic character of KCl.

In the van der Waal's equation (P + $${{{n^2}a} \over {{V^2}}}$$)(V - nb) = nRT the constant 'a' reflects the actual volume of the gas molecules.