Which among the following crystal lattices occupies all of the cubic holes by cations?

Silver crystallises in fcc structure, if edge length of unit cell is 316.5 pm . What is the radius of silver atom?

An element crystallises in a bcc lattice with cell edge of 500 pm. The density of the element is $$7.5 \mathrm{~g} \mathrm{~cm}^{-3}$$. How many atoms are present in 300 g of metal?

An element has a bcc structure with cell edge of 288 pm . The density of element is $$7.2 \mathrm{~g} \mathrm{~cm}^{-3}$$. What is the atomic mass of an element?