A liquid was mixed with ethanol and a drop of concentrated ${\mathrm{H}}_2{\mathrm{SO}}_4$ was added. A compound with a fruity smell was formed. The liquid was

Sodium phenoxide when heated with ${\mathrm{CO}}_2$ under pressure at $125°\mathrm{C}$ yields a product which on acetylation produces $\mathrm{C}$,    

The major product $\mathrm{C}$ would be:

The major product of the following reaction is:

The major product of the following reactions is:

Arrange the following compounds in order of decreasing acidity.

The most suitable reagent for the conversion of $\mathrm{R}-{\mathrm{CH}}_{\mathrm{2}}-\mathrm{OH}\stackrel{}{\to }\mathrm{R}-\mathrm{CHO}$ is _____.