Read the passage carefully and answer the questions.

Alcohols and phenols are formed when a hydrogen atom in a hydrocarbon, aliphatic and aromatic respectively is replaced by - OH group. These are further classified on the basis of number of hydroxy groups and according to the hybridization of the carbon atom $sp^2$ or $sp^3$ to which the -OH group is attached. They find applications in industry as well as in day-to-day life. One of the most commercially obtained alcohol also known as wood spirit is obtained by destructive distillation of wood. Both alcohols and phenols are acidic in nature. The acidity of alcohols and phenols vary according to the nature of substituent(s) attached to them. Alcohols and phenols react with carboxylic acids, acid chlorides and acid anhydrides to form esters. Introduction of acetyl group in alcohols and phenols is called acetylation. Phenol undergo electrophilic aromatic substitution reaction because the -OH activates the benzene ring. It undergoes nitration, halogenation and sulphonation reactions.

Which of the following compound lacks a phenolic group?

Glycerol

The correct answer is Option (2) → Glycerol **

A phenolic group refers to a hydroxyl group (–OH) directly attached to an aromatic benzene ring. Compounds containing this functional group are called phenols.

Thus, to answer the question we check whether the –OH group is attached to a benzene ring.

Option-wise Explanation

Option 1: Quinol

Quinol (hydroquinone) contains two –OH groups attached to a benzene ring in the para position. Hence it is a phenolic compound.

Option 2: Glycerol

Glycerol is an aliphatic triol with the structure:

HO–CH₂–CH(OH)–CH₂–OH

Although it contains three –OH groups, none of them are attached to an aromatic ring. Therefore it does not contain a phenolic group.

Option 3: Resorcinol

Resorcinol is benzene-1,3-diol, which has two hydroxyl groups directly attached to the benzene ring. Hence it contains phenolic groups.

Option 4: Cresol

Cresol is methylphenol, where a methyl group and a hydroxyl group are attached to a benzene ring. Therefore it is a phenolic compound.