What is a face-centred cubic unit cell?

Lithium iodide crystal has a face-centred cubic unit cell. If the edge length of the unit cell is 620 pm, determine ionic radius of I^(-) ions.

The number of atoms/molecules contained in one face centred cubic unit cell of a monoatomic substance is:

Copper crystallises with face centred cubic unit cell. If the radius of copper atom is 127.8 pm, calculate the density of copper metal. (Atomic mass of Cu= 63.55 u and Avogadro's number, N_(A)=6.02xx10^(23)"mol"^(-1) )

The edge of the face centred cubic unit cell of aluminium is 404 pm. Calculate the radius of aluminium atom.

The number of atoms/molecules present in one body centred cubic unit cell is:

Give the relationship between nearest neighbour distance (d) and radius (r) of an atom with edge length (a) of a face-centred cubic system.