A) Less than in the second case by \[1.89\,kJ\]
B) More than in the second case by \[1.89\,kJ\]
C) Less than in the second case by \[11.34\,kJ\]
D) More than in the second case by \[0.945\,kJ\]
Correct Answer: D
Solution :
\[{{C}_{(\text{graphite})}}\to {{C}_{(\text{diamond})}},\Delta H=1.9\,kJ\] \[{{C}_{(\text{graphite})}}+{{O}_{2}}\to C{{O}_{2}},\Delta H=-\Delta {{H}_{1}}\] \[{{C}_{(\text{diamond})}}+{{O}_{2}}\to C{{O}_{2}},\,\Delta H=-\Delta {{H}_{2}}\] \[(\,-\Delta {{H}_{1}})-(\,-\Delta {{H}_{2}})=1.9\,kJ\] or \[\Delta {{H}_{2}}=\Delta {{H}_{1}}+1.9\] For combustion of \[6g,\Delta {{H}_{2}}>\Delta {{H}_{1}}\] by \[1.9/2=0.95\,kJ.\]
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