$\left[ {\begin{array}{*{20}{c}}
\begin{gathered}
4(C - H\,) \hfill \\
\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, + \hfill \\
\end{gathered} \\
\begin{gathered}
C = C \hfill \\
\,\,\,\,\,\,\,\,\, \,\, + \, \hfill \\
\end{gathered} \\
\begin{gathered}
{\text{H - H}}\, \hfill \\
\,\,\,\,\,\,\,\,\,\,\,\,\, + \hfill \\
\end{gathered}
\end{array}} \right]\,\, - \,\,\left[ {\begin{array}{*{20}{c}}
\begin{gathered}
6(C - H\,) \hfill \\
\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, + \hfill \\
\end{gathered} \\
{{\text{C - C}}\,}
\end{array}} \right]$
$= [4(414) + 615 + 435] - [ 6(414) + 347] = -125$ જૂલ
$A + B \rightleftharpoons C+D$
$27^{\circ}\,C$ પર પ્રમાણિત મુક્ત ઊર્જા ફેરફાર $\left(\Delta_{ r } G ^0\right)$ $(-)$ $............kJ mol ^{-1}$ છે. (નજીકની પૂર્ણાંક)
(આપેલ : $R =8.3\,Jk ^{-1}\, mol ^{-1}$ અને In $10=2.3$ )