An atom crystallises in fcc crystal lattice and has a density of $10 \mathrm{g} {\mathrm{cm}}^{-3}$ with unit cell edge length of $100 \mathrm{pm}$. Calculate number of atoms present in $1 \mathrm{g}$ of crystal.

How many lattice points are in unit cells of following lattices? 

Face -centred cubic 

Calculate the efficiency of close packing in case of a metal crystal for

Simple cubic.

Calculate the efficiency of close packing in case of a metal crystal for Body-centred cubic ?

Calculate the efficiency of close packing in case of a metal crystal for:

Face-centred cubic