A 10L flask contains 41.4g of a mixture of gases $C_x{H}_8$ and $C_x{H}_{12}$.  The total pressure of ${44}^{0}C$ in the flask is 1.56 atm.  Analysis revealed that the gas mixture has 87% total carbon and 13% total H.  The value of ‘X’.

From PV=nRT, total moles =0.6.

Let $C_x{H}_8$ be ‘a’ mole therefore moles of $C_x{H}_{12}=\left(0.6-a\right)$ mole

Mass of ‘c’ in ‘a’ mole of $C_x{H}_8=12axg$.

Mass of ‘c’ in $\left|0.6-a\right|$ mole of $C_x{H}_{12}=12\left(0.6-a\right)g$.

Therefore total mass of c in mixture = 41.4g and x=5.