What is the total number of spheres that surrounds the tetrahedral hole in the close-packed three-dimensional structure?

Which of the following is a green alternative for dry cleaning solvents?

Vapour pressure of $\text{CCl}_4$ at $25^\circ$C is $143$ mm Hg. If $0.5$ g of a non-volatile solute is dissolved in $100 \text{ cm}^3$ of $\text{CCl}_4$. Find the vapour pressure of the solution.
(Density of $\text{CCl}_4 = 1.58 \text{ g}/\text{cm}^3$ and molecular weight of solute is $65$)

The solubility of $\text{N}_2$ gas in water at $25^\circ$C and $1$ bar is $6.85 \times 10^{-4} \text{ mol L}^{-1}$. Calculate the solubility of $\text{N}_2$ gas in water at the same temperature when the partial pressure of $\text{N}_2$ is $0.70$ bar