How many particles per unit cell are present in $$\mathrm{BCC}$$ structure?

An element with BCC structure has edge length of $$500 \mathrm{~pm}$$. If it's density is $$4 \mathrm{~g} \mathrm{~cm}^{-3}$$, find atomic mass of the element?

What is the atomic radius of polonium if it crystallises in a simple cubic structure with edge length of unit cell $$336 \mathrm{~pm}$$ ?

Identify the type of unit cell that has particles at the centre of each face in addition to the particles at eight corners of a cube?