Calculate the number of unit cell in $1 \mathrm{~cm}^3$ volume of metal if volume of unit cell is $3.448 \times 10^{-23} \mathrm{~cm}^3$

Calculate the volume of fcc unit cell in $\mathrm{cm}^3$ if void volume of it is $4.16 \times 10^{-24} \mathrm{~cm}^3$.

Calculate the number of atoms present per unit cell if product of density and volume of unit cell is $1.8 \times 10^{-22} \mathrm{~g}$.

[Mass of an atom $=4.5 \times 10^{-23} \mathrm{~g}$ ]

Identify the defect developed when an ion of an ionic compound is missing from its regular site and occupies interstitial position between lattice points.