The general combustion equation for a hydrocarbon $C_xH_y$ requires how many moles of oxygen?

1. Complete combustion gives carbon dioxide and water: $C_xH_y+O_2\rightarrow xCO_2+\dfrac{y}{2}H_2O$. 2. Balance the carbon first: $x$ carbons give $x$ molecules of $CO_2$, needing $x$ molecules of $O_2$. 3. Balance the hydrogen: $y$ hydrogens give $\dfrac{y}{2}$ molecules of water, which carry $\dfrac{y}{2}$ oxygen atoms. 4. Those $\dfrac{y}{2}$ atoms come from $\dfrac{y}{4}$ molecules of $O_2$. 5. Adding the two requirements gives $\left(x+\dfrac{y}{4}\right)$ moles of oxygen. _Source: NECTA ACSEE 2024 Chemistry 132/1, Question 1: Aliphatic Hydrocarbons_