An organic compound gives a silver mirror with Tollens reagent, does not reduce Fehling solution and, when treated with concentrated $\mathrm{NaOH}$, gives an alcohol and the sodium salt of an acid. The compound is

Tollens positive indicates an aldehyde; Fehling negative points to an aromatic aldehyde. An aldehyde with no alpha hydrogen undergoes the Cannizzaro reaction in conc. alkali: $2\mathrm{C}{}_6\mathrm{H}{}_5\mathrm{CHO}$ gives $\mathrm{C}{}_6\mathrm{H}{}_5\mathrm{CH}{}_2\mathrm{OH}$ and $\mathrm{C}{}_6\mathrm{H}{}_5\mathrm{COONa}$. Ethanal and propanal have alpha hydrogens and would undergo aldol reaction, and propanone does not reduce Tollens reagent.