1. Acetaldehyde gives silver mirror test with Tollens’ regent where as acetone does not.
CH3 – CHO + 2 [Ag (NH3)2]+ OH →
CH3CHOONH4 + 2 Ag + 3NH3 + H2O
2. Treat each compound with sodium carbonate solution. Benzoic acid decomposes NaHCO, to evolve CO2, but phenol does not.
C6H5COOH + NaHCO3 → C6H5COONa + CO2 ↑+ H2O
3. Treat each compound with 2,4- DNP reagent. Only propanone gives an orange colour ppt