When a hydrocarbon A undergoes complete combustion it requires 11 equivalents of oxygen and produces 4 equivalents of water. What is the molecular formula of A?

Given that a hydrocarbon under complete combustion consume 11equivalent of oxygen and produces 4 equivalents of H₂O
$\therefore$According to given data, the hydrocarbon is ${\mathrm{C}}_9{\mathrm{H}}_8:{\mathrm{C}}_9{\mathrm{H}}_8+11{\mathrm{O}}_2\to 9{\mathrm{CO}}_2+4{\mathrm{H}}_2\mathrm{O}$