The decreasing order of electron affinity of F, Cl, Br is F > Cl >Br

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

The dipole moment of CH₃F is greater than of CH₃Cl

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