Which is the incorrect statement ?
(1) Frenkel defect is favoured in those ionic compounds
in which sizes of cation and anions are almost equal
(2) FeO0.98 has non stoichiometric metal deficiency defect
(3) Density decreases in case of crystals with Schottky's defect
(4) NaCl(s) is insulator, silicon is semiconductor, silver
is conductor, quartz is piezo electric crystal