Part b compare the bond enthalpies of the nitrogen-nitrogen single and triple bonds. based on this information, what is the average π-bond contribution to bond enthalpy in n≡n? express your answer with the appropriate units.

C-C bonds = 348 C=C bonds = 614 C(triple) bonds = 839 
All in KJ/Mol 
just do 839-614=225 and 614-348=266 
After a pi bond is added on, these two numbers are the KJ/Mol it takes to separate the C-C bond,  
To get the average: (225+266)/2 = 245.5Kj/Mol 
You might want to round your answer to 246KJ/Mol