Answers

2016-02-10T22:39:21+05:30
The functional groups are those whose formula is generally same and functions the same..
ALCOHOL = OH
ALDEHYDES= R-CHO
KETONES=C=O
CARBOXYLIC-COOH
0
2016-02-10T23:28:22+05:30
Functional group is an atom or group of atoms within a molecule that determine the properties of the molecule and reactions in which it takes part.

Functional group present in alcohols, aldehydes, ketones and carboxylic acids are:
Alcohols : hydroxyl group (OH) 
Aldehydes : aldehydic group (CHO) 
Ketones : ketonic group (C=O) 
Carboxylic acid : carboxyl group (COOH) 
1 5 1
Hope it helps :) and if it does please click on thanks button above & mark as best answer ^_^