\[{{C}_{2}}{{H}_{6}}(g)+3.5{{O}_{2}}(g)\to 2C{{O}_{2}}(g)+3{{H}_{2}}O(g)\]\[\Delta {{S}_{vap}}({{H}_{2}}O,\ell )={{x}_{1}}cal\,{{K}^{-1}}\] (boiling point = \[{{T}_{1}}\]) \[\Delta {{H}_{f}}({{H}_{2}}O,\ell )={{x}_{2}}\] \[\Delta {{H}_{f}}({{C}_{2}}O,)={{x}_{2}}\] \[\Delta {{H}_{f}}({{C}_{2}}{{H}_{6}},)={{x}_{4}}\] Hence, \[\Delta H\] for the reaction is

• A.  \[2{{x}_{3}}+3{{x}_{2}}-{{x}_{4}}\]
• B.  \[2{{x}_{3}}+3{{x}_{2}}-{{x}_{4}}+3{{x}_{1}}{{T}_{1}}\]
• C.  \[2{{x}^{+}}+3{{x}_{2}}-{{x}_{4}}+3{{x}_{1}}{{T}_{1}}\]
• D.  \[{{x}_{1}}{{T}_{1}}+{{x}_{2}}+{{x}_{3}}-{{x}_{4}}\]