E) H$_2$SO$_4$
4. If the $\Delta H^\circ$ for the reaction, 2 Mg$_{(s)}$ + 2 Cl$_{2(g)}$ $\rightarrow$ 2 MgCl$_{2(s)}$, is -1283.6 kJ, what is the standard enthalpy of formation of magnesium chloride?
A) 0 kJ/mol
B) -320.9 kJ/mol
C) -641.8 kJ/mol
D) 1283.6 kJ/mol
E) -1283.6 kJ/mol
