A compound forms hcp structure. What is the number of tetrahedral voids formed in 0.8 mol of it.

Calculate the number of atoms present in 90 g of metal if it forms bcc structure.
[ $\rho \times a^3 = 1.8 \times 10^{-22}$ g ]

In the fcc structure, the number of tetrahedral holes per sphere is

For a binary solution, when a nonvolatile nonelectrolyte solute is dissolved in solvent, the vapour pressure of solvent decreases by 20 % . what is mole fraction of solvent in solution ?