Answer
$C_{6}H_{6}$
Work Step by Step
Number of moles of the compound
$n=\frac{PV}{RT}=\frac{(0.74\,atm)(97.2\times10^{-3}\,L)}{(0.0821\,L\,atm\,K^{-1}mol^{-1})(200+273)K}$
$=0.0018522\,mol$
Molar mass= $\frac{\text{mass in grams}}{n}=\frac{0.145\,g}{0.0018522\,mol}=78.285\,g/mol$
As the molecular formula is a multiple of empirical formula, the molar mass is also a multiple of empirical formula mass.
To know by what number the empirical formula is multiplied, we divide molar mass by empirical formula mass.
$\frac{\text{molar mass}}{\text{empirical formula mass}}=\frac{78.285\,g/mol}{(12+1)g/mol}=6.0$
Then, Molecular formula= $C_{6}H_{6}$
