Determine the fuel model cnhm- the composition of the fuel

Question

An unknown hydrocarbon material is burned in a calorimeter with air. An Orsat analysis indicates that the (dry) exhaust gas is made up of only 17.5% CO₂ and 82.5% N₂, with no CO or O₂ present. Determine

a. The fuel model (C_nH_m).

b. The composition of the fuel on a mass basis.

c. The percent theoretical air used.

d. The dew point temperature if the combustion products are at 0.101 MPa.