Identify '$$\mathrm{A}$$' and '$$\mathrm{B}$$' in the following reaction.

$$\mathrm{CH}_3 \mathrm{Br} \stackrel{\mathrm{AgNO}_2}{\longrightarrow} \mathrm{A} \stackrel{\mathrm{Sn} / \mathrm{HCl}}{\longrightarrow} \mathrm{B}$$

Calculate the molar mass of metal having density $$9.3 \mathrm{~g} \mathrm{~cm}^{-3}$$ that forms simple cubic unit cell. $$\left[\mathrm{a}^3 \cdot \mathrm{N}_{\mathrm{A}}=22.6 \mathrm{~cm}^3 \mathrm{~mol}^{-1}\right]$$

Calculate the $$\mathrm{E}_{\text {cell }}^{\circ}$$ for $$\mathrm{Zn}_{(\mathrm{s})}\left|\mathrm{Zn}_{(\mathrm{IM})}^{++}\right|\left|\mathrm{Cd}_{(\mathrm{IM})}^{++}\right| \mathrm{Cd}_{(\mathrm{s})}$$ at $$25^{\circ} \mathrm{C}\left[\mathrm{E}_{\mathrm{Zn}}^0=-0.763 \mathrm{~V} ; \mathrm{E}_{\mathrm{Cd}}^{\circ}=-0.403 \mathrm{~V}\right]$$

What is the work done during oxidation of 4 moles of $$\mathrm{SO}_{2(\mathrm{~g})}$$ to $$\mathrm{SO}_{3(\mathrm{~g})}$$ at $$27^{\circ} \mathrm{C}$$?

$$\left(\mathrm{R}=8.314 \mathrm{~J} \mathrm{~K}^{-1(\mathrm{~g})} \mathrm{mol}^{-1}\right)$$