Identify the angle $\mathrm{O}-\mathrm{S}-\mathrm{O}$ in $\mathrm{SO}_2$ molecule.

Calculate the number of unit cells in 0.9 g metal if it forms bec structure. $\left[\rho \times \mathrm{a}^3=3 \times 10^{-22}\right.$ gram$]$

Which of the following polymers need $\mathrm{HO}-\mathrm{CH}_2-\mathrm{CH}_2-\mathrm{OH}$ as one of the monomers for its preparation?

What is the EAN of Zn in $\left[\mathrm{Zn}\left(\mathrm{NH}_3\right)_4\right]^{2+}$ ?