\({\text{(1)}}\,\,{{\text{C}}_{{\text{Diamond}}}}\, \to \,\,{C_{graphite}};\,\,\,\,\,\,\,\,\Delta H\,\, = \,\,?\)

\((2)\,\,{C_{Diamond}}\,\, + \,\,{O_2}\, \to \,\,C{O_2}\,;\,\,\,\,\,\,\,\Delta H\, = \,\, - 395.4\,KJ\)  

\(\begin{gathered}
  (3)\,\,\underline {{C_{graphite}}\,\, + \,\,{O_2}\,\, \to \,\,C{O_2}\,;\,\,\,\,\,\,\,\Delta H\, = \,\, - \,393.5\,\,KJ} \,\,\,\, \hfill \\
  \,\,\,\,\,\,\,\,\,{C_{Diamond}}\, - \,\,{C_{graphite}}\,\, \to \,\,O\,\,\,\,\,\,\Delta H\,\, = \,\, - \,1.9\,\,KJ \hfill \\
  \,\,\,\,\,\,\,\,\,{C_{Diamond}}\, \to {C_{graphite}}\,;\,\,\,\,\,\,\,\Delta H\,\,\, = \,\, - \,1.9\,\,KJ \hfill \\ 
\end{gathered} \)  સમીકરણ \(2\) માથી સમીકરણ \(3\) બાદ કરતાં,