Standard enthalpy of combustion of benzene, graphite and hydrogen are $-3276 \mathrm{kJ} {\mathrm{mole}}^{-1}$, $-394 \mathrm{kJ} {\mathrm{mole}}^{-1}$ and $-286 \mathrm{kJ} {\mathrm{mole}}^{-1}$ respectively.  Standard enthalpy of formation of benzene is ___$\mathrm{kJ} {\mathrm{mole}}^{-1}$

$C_6{H}_6+\frac{15}{2}{O}_2\to 6C{O}_2+3H_{2}O ...\left(I\right)$

$\Delta H=-3276$

$C+O_2\to C{O}_2 ...\left(II\right)$$;\Delta H=-394$

$H_2+\frac{1}{2}{O}_2\to H_{2}O ...\left(III\right)$$;\Delta H=-286$

$\begin{array}{l}6C{O}_2+3H_{2}O\to C_6{H}_6+\frac{15}{2}{O}_2\Delta H=+3276\\ 6C +6O_2 \to 6C{O}_2\Delta H=-394\times 6=-2364\\ \underset{¯}{3H_2+\frac{3}{2}{O}_2\to 3H_{2}O}\Delta H=-286\times 3=-858\\ 6C+ 3H_2\to C_6{H}_6\end{array}$