Which functional group are present in the family of (i) alcohols (ii) aldehydes (iii) carboxylic acids?

The functional group present in aldehydes is -

Define a functional group. Give functional groups for (i) aldehydes (ii) carboxylic acid families.

State the meaning of functional group an organic compound. Write the formula of the functional group present in alcohols, aldehydes, ketones and carboxylic acids.

The functional group present in butanal is carboxylic acid.