Read carefully all the three statements on defects in solids: (i)...

Read carefully all the three statements on defects in solids: (i) In Frenkel defect, interstitial $\mathrm{Ag}^{+}$site is surrounded tetrahedrally by four $\mathrm{Cl}^{-}$ions and four $\mathrm{Ag}^{+}$ions, where interstitial $\mathrm{Ag}^{+}$and $\mathrm{Cl}^{-}$interaction is covalent (ii) Addition of small amount of $\mathrm{SrCl}_2$ in NaCl yields solid solution with a formula of $\mathrm{Na}_{1-2 \mathrm{x}} \mathrm{Sr}_{\mathrm{x}} \mathrm{V}_{\text {Nax }} \mathrm{Cl}$, where $\mathrm{V}=$ valency (iii) In general, Schottky defect increases the density of the substance Choose the correct alternative(s).