A gaseous mixture of propane and butane of volume $3$ litre on complete combustion produces $11.0$ litre $C{O}_2$ under standard conditions of temperature and pressure. The ratio of volume of butane to propane is:

The correct option is B $2:1$
Consider, volume of propane is V
$\underset{V}{C_3{H}_8}+\underset{5V}{5O_2}\to \underset{3V}{3C{O}_2}+4H_{2}O$
$\underset{3-V}{C_4{H}_{1}0}+\underset{\frac{13}{2}(3-V)}{5O_2}\to \underset{4(3-V)}{4C{O}_2}+4H_{2}O$
3L of propane and butane reacts with oxygen to give 11 L of $C{O}_2$
3V+ 4(3-V)=11
Volume of propane V=1
Volume of butane 3-1=2
Ratio of volume of butane to propane that reacts with oxygen is 2:1