A mixture of CO and $C{O}_2$ is found to have a density of 159 g/litre at ${30}^{o}C$ and 730mm. The % mole composition of CO is (as nearest integer).

The molar mass of mixture of CO and $C{O}_2$ can be obtained in two ways .The comparison of two moles gives values of each

(I) Let $n_1$ mole of CO and $(100-n_1)$ mole of $C{O}_2$ are presented in 100 mole

avg molar mass=$\frac{n_1\ast 28+(100-n_1)\ast 44}{100}$

(II) Also for mixture P=(730/760)atm T=303K ,d=$1.50glitr{e}^{-}1$

PV=$\frac{W}{m}RT$

P=$\frac{W}{Vm}RT$

$\frac{730}{760}$ =$\frac{1.50}{M}$*0.821*303

M=$38.85gmo{l}^{-}1$

A comparison of equation (1) and (ii) yields $n_1$=32.19

mole % of CO=32.190

and Mole % of $C{O}_2$=67.81

so nearest integer is 32.