What is the common name of the given compound: CH₂(OH)-CH(OH)-CH₂(OH) ?

Glycerol

The correct answer is option 2. Glycerol.

The common name of the compound CH₂(OH)-CH(OH)-CH₂(OH) is Glycerol

This compound is also known by its IUPAC name, propane-1,2,3-triol. It is a colorless, odorless, viscous liquid that is soluble in water and many other organic solvents. Glycerol has a sweet taste and is hygroscopic, meaning it readily absorbs moisture from the air.

Here is why the other options are not correct:

Propylene glycol: This is a diol (two hydroxyl groups) with a different structure (CH₂OH-CHOH-CH₃).

Cresol: This is a type of aromatic alcohol with a methyl group attached to a benzene ring and a single hydroxyl group.