The order is :
\(\mathrm{CH}_3 \mathrm{CH}_2 \mathrm{CH}_3 < \mathrm{CH}_3 \mathrm{OCH}_3 < \mathrm{CH}_3 \mathrm{CHO} < \mathrm{CH}_3 \mathrm{CH}_2 \mathrm{OH}\)
All these compounds have comparable molecular masses \(\mathrm{CH}_3 \mathrm{CH}_2 \mathrm{OH}\) undergoes extensive intermolecular \(\mathrm{H}\)-bonding and thus its b.pt. is the highest. \(\mathrm{CH}_3 \mathrm{CHO}\) is more polar than \(\mathrm{CH}_3 \mathrm{OCH}_3\) so that dipole-dipole interactions in \(\mathrm{CH}_3 \mathrm{CHO}\) are greater than in \(\mathrm{CH}_3 \mathrm{OCH}_3\). weak van der waals forces between its molecules and hence has the lowest b.pt.