Alkenes on oxidation with $\text{KMnO}_4$ in dil $\text{H}_2\text{SO}_4$ forms

Find the volume occupied by a particle in a simple cubic unit cell if the radius of a particle in it is 190 pm.

Calculate the number of unit cells in $1\text{cm}^3$ of metal if it forms simple cubic structure with unit cell edge length 500 pm.

Which of the following concentrations of solutions of urea in water exhibits minimum freezing point depression?