# A gas mixture of $3l$ of propane $(C_3H_8)$ and butane $C_4H_{10}$ on complete combustion at $25C^{\large\circ}$ produced $10l$ $CO_2$.Find out the composition of gas mixture.
$(a)\;2l,1l\qquad(b)\;3l,2l\qquad(c)\;4l,3l\qquad(d)\;2l,3l$