Question

A sample of $C_3{H}_4$ and $C_5{H}_{12}$ gas has $d$%, by mass of $C_3{H}_4$. If the average molar mass of the sample is 200/3 gm, then the value of '$d$' is:

• A. $0.1$
• B. $10$
• C. $\frac{1}{6}$
• D. $20$

Answer 1

The correct option is C $\frac{1}{6}$

Molar mass of $C_3{H}_4:40$

Molar mass $C_5{H}_2=72$

$40d+72\left(1.d\right)=\frac{200}{3}$

$40d\to 72-72d=\frac{200}{3}$

$72-\frac{200}{3}=32d$

$\frac{16}{3}-32d$

$d=\frac{1}{6}$