Which of the following is trihydric phenol?

Step-by-step solution

Phenols are classified by the number of hydroxyl groups bonded to the benzene ring: monohydric (one -OH ), dihydric (two -OH ), or trihydric (three -OH ). Catechol (benzene-1,2-diol), resorcinol (benzene-1,3-diol), and quinol (benzene-1,4-diol) are all dihydric phenols. Pyrogallol is benzene-1,2,3-triol and contains three hydroxyl groups. Thus, pyrogallol is the only trihydric phenol among the options.