At $\mathrm{T}(\mathrm{K})$, the vapour pressure of pure benzene (molar mass $=78 \mathrm{~g} \mathrm{~mol}^{-1}$ ) is $0.85 \mathrm{bar}$. When $2.0 \mathrm{~g}$ of non-volatile, non-electrolyte solute is added to $39 \mathrm{~g}$ of benzene, the vapour pressure of solution at $\mathrm{T}(\mathrm{K})$ is 0.83 bar. The elevation in boiling point (in $\mathrm{K}$ ) of the same solution is: $\left(\mathrm{K}_{\mathrm{b}}\right.$ of benzene is $2.6 \mathrm{~K} \mathrm{~kg} \mathrm{~mol}^{-1}$)