# A mixture of propane and butane are confined in a bottle with a small hole. What is the rate of effusion of butane with respect to butane?

Well, for $\text{LPG}$ more $\text{propane}$ would have been leaked than $\text{butane}$.
$\text{Liquefied petroleum gas}$, $\text{LPG}$, is typically a mixture of $\text{butane}$, ${C}_{4} {H}_{10}$, and $\text{propane}$, ${C}_{3} {H}_{8}$. This is a clean burning fuel with high heat output (combustion is fairly complete due to the short hydrocarbon chains). This problem could be quantified if you gave us the makeup of the gas, and the initial and end masses.