8g of sulphur is burnt to form SO₂ which is oxidized by chlorine water. The solution is treated with BaCl₂ solution. The number of moles of BaSO₄ precipitated is

$$\begin{gathered} \mathrm{S}+{\mathrm{O}}_2\to {\mathrm{SO}}_2 \\ {\mathrm{SO}}_2+{\mathrm{Cl}}_2+2{\mathrm{H}}_2\mathrm{O}\to {\mathrm{H}}_2{\mathrm{SO}}_4+2\mathrm{HCl} \\ {\mathrm{H}}_2{\mathrm{SO}}_4+{\mathrm{BaCl}}_2\to {\mathrm{BaSO}}_4+2\mathrm{HCl} \\ {\mathrm{n}}_{{\mathrm{SO}}_2}=\frac{8}{32}=0.25\mathrm{moles} \\ \mathrm{From} \mathrm{the} \mathrm{series} \mathrm{of} \mathrm{reactions}, \\ 1\mathrm{mole} \mathrm{of} \text{'}\mathrm{S}\text{'} \to 1\mathrm{mole} \mathrm{of} {\mathrm{BaSO}}_4 \\ 0.25\mathrm{moles} \mathrm{of} \text{'}\mathrm{S}\text{'} \to ? \\ =0.25\mathrm{moles}. \end{gathered}$$