Account for the following :
(i) Schottky defects lower the density of related solids.
(ii) Conductivity of silicon increases on doping it with phosphorus.

Explanation

(i) As equal no. of cationic and anionic sites are-found vacant. Hence elensity-decreases.
(ii) Pure.Silicon's resistance is quite high. It is an extremely important semiconductor. It is doped with boron, phosphorus, or arsenic, to increase its conductivity. Conductivity increases due to extra free delocalised electrons.