The value of \[{{\Delta }_{f}}G{}^\circ \] for formation of \[C{{r}_{2}}{{O}_{3}}\] is \[-540\text{ }kJmo{{l}^{-1}}\] and that of \[A{{l}_{2}}{{O}_{3}}\] is \[-827\text{ }kJ\text{ }mo{{l}^{-1}}\] What is the value of \[{{\Delta }_{f}}G{}^\circ \] for the reaction? \[\frac{4}{3}Al(s)+\frac{2}{3}C{{r}_{2}}{{O}_{3}}(s)\to \frac{2}{3}A{{l}_{2}}{{O}_{3}}(s)+\frac{4}{3}Cr(s).\]

• A. \[-574\text{ }kJ\,mo{{l}^{-1}}\]           
• B. \[-287\,kJ\,mo{{l}^{-1}}\]
• C. \[+574\text{ }kJ\,mo{{l}^{-1}}\]   
• D. \[+287kJ\,mo{{l}^{-1}}\]