Read carefully all the three statements on defects in solids. 

(i) In Frenkel defect, interstitial $$\text{Ag}^+$$ site is surrounded tetrahedrally by four $$\text{Cl}^-$$ ions and four $$\text{Ag}^+$$ ions, where the interstitial $$\text{Ag}^+$$ and $$\text{Cl}^-$$ interaction is covalent. 

(ii) Addition of small amount of $$\text{SrCl}_2$$ in NaCl yields solid solution with a formula of $$\text{Na}_{1-2x}\text{Sr}_x\text{V}_{\text{Na},x}\text{Cl}$$, where V is valency. 

(iii) In general, Schottky defect increases the density of the substance. 

Choose the correct alternative or alternatives.