A compound has fcc structure. If density of unit cell is $$3.4 \mathrm{~g} \mathrm{~cm}^{-3}$$, what is the edge length of unit cell?

(Molar mass $$=98.99$$)

Xenon crystallises in fcc lattice and the edge length of unit cell is 620 pm. What is the radius of Xe atom?

If a metal crystallises in bcc structure with edge length of unit cell $4.29 \times 10^{-8} \mathrm{~cm}$ the radius of metal atom is

Which among the following statements is true about Schottky defect?