A metallic element crystallises in simple cubic lattice. If edge length of the unit cell is $$3\mathop A\limits^o$$, with density $$8 \mathrm{~g} / \mathrm{cc}$$, what is the number of unit cells in $$100 \mathrm{~g}$$ of the metal?

(Molar mass of metal $$=108 \mathrm{~g} / \mathrm{mol}$$ )

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?