Calculate elevation of the boiling point of the solution when $4 \text{ g}$ of $\text{MgSO}_4$ (molar mass = $120 \text{ g/mol}$) was dissolved in $100 \text{ g}$ of water, assuming $\text{MgSO}_4$ undergoes complete ionisation. ($K_b$ for water = $0.52 \text{ K kg mol}^{-1}$)