Phenol is manufactured from hydrocarbon, Cumene. Cumene is chemically:

The correct answer is option 2. Isopropyl benzene.

Cumene, chemically known as isopropylbenzene, is an organic compound with the chemical formula \(\text{C}_9\text{H}_{12}\). It consists of a benzene ring substituted with an isopropyl group (\( \text{CH}_3\text{-}CH(\text{CH}_3)\text{-}\)).

The synthesis of phenol from cumene involves a process known as cumene hydroperoxide process or Hock process. Here's a brief explanation of the process:

1. Oxidation of Cumene: Cumene is oxidized using oxygen or air in the presence of an acid catalyst, typically a solid acidic catalyst like aluminum silicate supported by a metal oxide. This oxidation reaction forms cumene hydroperoxide (\( \text{C}_6\text{H}_5\text{-}CH(\text{CH}_3)\text{-}\text{OOH} \)).

2. Cleavage of Cumene Hydroperoxide: The cumene hydroperoxide is then subjected to cleavage in the presence of an acid catalyst, which breaks the O-O bond, yielding phenol and acetone as the main products.

The overall reaction can be represented as follows:

The phenol obtained from this process can then be further processed and purified for various industrial applications, such as the production of plastics, resins, pharmaceuticals, and various chemicals.