C₂H₅CHO and CH₃COCH₃ can be distinguished from one another by testing with

Fehling's A is a solution containing copper(II) sulphate, which is blue color. Fehling's B is a clear liquid consisting of potassium sodium tartrate (Rochelle salt) and a strong alkali like NaOH,KOH.,Etc, usually sodium hydroxide. During the test solutions A and B are prepared individually and stored. Just before the test they are mixed. Aldehyde give red ppt and ketones do not respond.