Are colligative properties applicable for volatile liquids and gases in liquid solvent? Why/Why not?

My teacher told me that the expressions for calculation of colligative properties like lowering in freezing point are only applicable if the solute is non volatile liquid or a solid. We cannot apply the formula for gases or volatile liquids. Is this true? If so then why/ why not?

I have not been able to come up with a satisfying reasoning explaining this statement. Also I have not been able to find evidence regarding this statement online. Although one of my books does say this without an explanation but I am not convinced.

• Well, if somethin's gonna boil off before your solvent then it can hardly influence b.p. like salt will... – Mithoron Jul 18 at 19:28
• @Mithoron Solute doesnt necessarily need to have a boiling point lower than solvent. Also what about gas in liquid mixtures. – Manit Agarwal-El psy congroo Jul 20 at 2:39