Answer:
The complete combustion of cyclopropane is:
2CâHâ Â + Â 9Oâ Â â Â 6COâ Â + Â 6HâO
5914.3kcal are realeased in the  combustion of 497 g of cyclopropane
Explanation:
Heat of combustion = 499.8 kcal/mol
This data means that 1 mol of CâHâ release 499.8 kcal.
Let's convert the mass to moles (mass / molar mass)
497 g / 42g/mol = 11.83 moles
Let's make a rule of three:
1 mol ____ 499.8
11.83 moles _____ (11.83 Â .499.8)/1 =5914.3kcal