$\begin{array}{1 1}\Delta T_b=K_bm\;where\;K_b=M_1RT_b^{*2}/\Delta_{vap}H_m\\\Delta T_b=K_bm\;where\;K_b=RT_b^{*2}/M_1\Delta_{vap}H_m\\\Delta T_b=K_bm\;where\;K_b=M_1T_b^{*2}/R\Delta_{vap}H_m\\\Delta T_b=K_bm\;where\;K_b=M_1RT_b^{*2}\Delta_{vap}H_m\end{array} $