(3) A carboxylic acid is an organicacid characterized by thepresence of at least one carboxylgroup. They are the mostcommon type of organic acid.Among the simplest examplesare formic acid which occursin ants, and acetic acid whichgives vinegar its sour taste.Other important natural examplesare citric acid (in lemons)and tartaric acid (in tamarinds).Picric acid is an acidicphenol.