Explanation

 Hydroxylation of alkene can be carried out by  alkaline KMnO4. 

Hydroxylation refers to the addition of two hydroxyl (OH) groups across a carbon-carbon double bond in an alkene.

Cold, dilute, alkaline potassium permanganate (KMnO4) is a common reagent used for this reaction.

It reacts with the alkene to form a vicinal diol (a molecule with two hydroxyl groups on adjacent carbon atoms).