Arrange the following compounds in the increasing order of their boiling points: Formaldehyde, ethane and methyl alcohol.

Observe the following equation of the reaction of Tollens’ reagent with an aldehyde. How do we know that a redox reaction has taken place. Explain.

$\mathrm{R}-\mathrm{CHO} + 2\mathrm{Ag}{{\left({\mathrm{NH}}_3\right)}_2}^{+}+{\mathrm{OH}}^{-}\stackrel{∆}{\to }\mathrm{R}-\mathrm{COO}{ }^{-}+ 2\mathrm{Ag} \downarrow + 4{\mathrm{NH}}_3 + 2{\mathrm{H}}_2\mathrm{O}$