The complete combustion of 1 mole of an acyclic hydrocarbon belonging to the homologous series with the general formula C _n H _ 2n requires exactly 4.5 moles of oxygen. The molecular formula of the hydrocarbon is:

Step-by-step solution

The general equation for the combustion of an alkene ( C _n H _ 2n ) is: C _n H _ 2n + 3n 2 O ₂ n CO ₂ + n H ₂ O Given that 1 mole of the hydrocarbon requires 4.5 moles of O ₂ , we can equate the stoichiometric coefficient of oxygen to 4.5 : 3n 2 = 4.5 3n = 9 n = 3 Substituting n = 3 into the general formula C _n H _ 2n , we get C ₃ H ₆ . Answer: C ₃ H ₆