Which is the incorrect statement?

A

NaCl(s) is insulator, silicon is semiconductor, silver is conductor, quartz is piezo electric crystal

B

Frenkel defect is favoured in those ionic compounds in which sizes of cation and anions are almost equal

C

$$FeO_{0.98}$$ has non stoichiometric metal deficiency defect

D

Density decreases in case of crystals with Schottky's defect