Statement-I : Density of an ionic solid decreases due to Frenkel defect.Statement-II: Packing efficiency of ccp structure is 68%.

I) Frenkel defect is a dislocation defect. One of the ion(generally cation) leaves the lattice point and occupies the interstitial site but does not leave the crystal, thus no change in the density of crystal.II) Packing efficiency of ccp structure is 74%.