Find ΔHrxn for the reaction:

5C(s)+6H2(g)→C5H12(g)

Use these reactions with known ΔH 's:
C5H12 (g) + 8O2 (g) -> 5CO2 (g) + 6H2O (g) ; ΔH = -3537 kJ
C (s) + O2 (g) -> CO2 (g) ; ΔH = -393.6 kJ
2H2 (g) + O2 (g) -> 2H2O (g) ; ΔH = 483.6 kJ