Answer
$C_7H_6N_2$
Work Step by Step
Raoult's Law:
$\Delta P=-\chi P^0\rightarrow \chi=-(94.16-95.26)/95.26=0.0115$
Number of moles of benzene: $10.0\ g\div78.11\ g/mol=0.128\ mol$
Number of moles of solute: $0.0115=n/(n+0.128)\rightarrow n=0.0015\ mol$
Molar mass: $0.177\ g\div 0.0015\ mol=118.84\ g/mol$
In 1 mol of the component:
$n_C\times12.01/118.84=71.17/100\rightarrow n_C=7.04\approx7$
$n_H\times1.01/118.84=5.12/100\rightarrow n_C=6.02\approx6$
$n_N\times14.01/118.84=23.17/100\rightarrow n_C=1.96\approx2$
Molecular formula: $C_7H_6N_2$
