[tex]\boxed{\begin{array}{c|c|c|c}\boxed{\bf Element}&\boxed{\bf No\:of\:moles}&\boxed{\bf Sample\:ratio}&\boxed{\bf Simplest\:ratio}\\ \sf C&\sf \dfrac{39.7}{12}=3.3&\sf \dfrac{3.3}{1.65}=2 &\sf 2\\ \sf H&\sf \dfrac{1.65}{1}=1.65&\sf \dfrac{1.65}{1.65}=1 &\sf 1\\ \sf O&\sf \dfrac{58.6}{35.5}=1.65 &\sf\dfrac{1.65}{1.65}=1&\sf 1\end{array}}[/tex]
Empirical formula mass=
[tex]\\ \sf\longmapsto 3(12)+1+35.5=36+1+35.5=37+35.5=72.5g[/tex]
[tex]\\ \sf\longmapsto n=\dfrac{Molecular\: formula\:mass}{Empirical\: formula\:mass}=\dfrac{181.5}{72.5}=2.503\approx 3[/tex]
molecular formula
[tex]\\ \sf\longmapsto 3(C3HCl)=C_9H_3Cl_3[/tex]