Calculate the number of atoms present in $1\ \text{g}$ metal that forms simple unit cell structure if product of density and volume of unit cell is $66.5 \times 10^{-24}\ \text{g}$

Calculate the void volume in fcc unit cell if total volume of a unit cell is $6.4 \times 10^{-23}\ \text{cm}^3$ ?

What is the total number of Bravais lattices in orthorhombic crystal system?

$40$ gram nonelectrolyte solute having molar mass $180\ \text{g mol}^{-1}$ dissolved in water has osmotic pressure $2\ \text{atm}$ at $300\ \text{K}$. Calculate the volume of solution. ($\text{R} = 0.0821\ \text{atm mol}^{-1}\text{K}^{-1}$)