The standard heat of formation $$\left( {{\Delta _f}H_{298}^0} \right)$$ of ethane (in kj/mol), if the heat of combustion of ethane, hydrogen and graphite are - 1560, -393.5 and -286 Kj/mol, respectively is :

For the reaction :

A($$l$$) $$ \to $$ 2B(g)

$$\Delta U = 2.1\,kcal,\,\Delta S = 20\,cal\,{K^{ - 1}}$$ at 300 K

Hence $$\Delta $$G in kcal is :