Ethers when dissolved in cold concentrated sulfuric acid forms,

Calculate the total volume occupied by all atoms in simple cubic unit cell if radius of atom is $3 \times 10^{-8} \mathrm{~cm}$.

Under similar conditions enthalpy of freezing is exactly opposite to

A buffer solution is prepared by mixing $0.2 \mathrm{~M} \mathrm{~NH} \mathrm{O}_4 \mathrm{OH}$ and $1 \mathrm{~M} \mathrm{~NH}_4 \mathrm{Cl}$. What is the pH value of buffer solution? $\left(\right.$ Give $\left.\mathrm{pK}_{\mathrm{b}}=7.744\right)$