Propane boilers are a common technology for domestic

Question

Propane boilers are a common technology for domestic heating, and have a typical energy efficiency of 90%. The chemical formula of propane is C₃H₈, its lower heating value is 50,400 kJ/kg, and its carbon content by mass is 82%:

a) How many kmol of CO₂ are generated by the combustion of 1 kmol of propane?

b) What are the direct CO₂ emissions for 1 MJ of heat generated by a propane boiler (units: kg of CO₂ per MJ of combusted propane)?