(a) Sodium sulphate-Ionic solids
Hydrogen-Molecular solid (non-planar)
(b) In ionic solid of AgCl, if `CdCl_(2)` is added as an impurity, they will create vacancies. `2Cd^(2+)` ion replaces onn `2Ag^(+)` ion to maintain electrical neutrality, and hence, `1Cd^(2+)` creates one vacancy.
(c)