Gold crystallizes as fcc unit cell, the edge length of unit cell is $408$ pm. What is the radius of gold atom?

What is the number of tetrahedral voids present in $0.5$ mole of compound forming hcp structure?

Which among the following pairs of solutions is isotonic in nature?

A solution of non volatile solute has boiling point elevation $0.70$ K if $K_b$ for the solvent is $2.44\ \text{K kg mol}^{-1}$. What is the molality of the solution?