In ionic solids, constituent particles are held together with strong electrostatic force of attraction along with their fixed position. The fixed position of ions and strong electrostatic force of attraction make ionic solids hard and brittle.
Give reasons for Cation vacancies in some crystals make them good catalysts.
The catalytic activity dependsvery much on the surface area per unit mass of the sample. Transition metal corresponds show metal deficiency due to absence of metal ion from its lattice. The charge is balanced by an adjacent ion having higher positive charge which ultimately increases chemisorption.