Question

The aromatic compounds present as particulates are:-
(a) Polycyclic aromatic hydrocarbons
(b) Benzene
(c) Toluene
(d) Nitrobenzene

Answer 1

We know that aromatic compounds are the compounds which consist of conjugated planar ring systems accompanied by delocalized pi-electron clouds in place of individual alternating double and single bonds. These compounds need to satisfy Huckel’s Rule of Aromaticity.

Complete step-by-step answer:
- Aromatic compounds, also known as arenes is a property of cyclic, planar structures with pi bonds in resonance (delocalization of pi electron clouds) that gives these compounds an increased stability compared to other connective or geometric structures with the same set of atoms. Also, these compounds are very stable and do not break apart easily.

- But these aromatic compounds tend to become harmful to the environment when they exist as particulate matter in air. These compounds become toxic and carcinogenic because their physical molecular structure contains 4 to 6 rings and certainly combines with genetic material of the organism and harms them.
- Polycyclic aromatic hydrocarbon is also one among these toxic particulate matters which has become a major research issue due to its increasing negative impacts on human life.
- A polycyclic aromatic hydrocarbon (denoted as PAH) is a hydrocarbon, chemical compound containing only carbon and hydrogen, which is composed of multiple aromatic rings. The simple examples of such chemicals are naphthalene (having two aromatic rings), and the three-ring compounds anthracene and phenanthrene.
- These are uncharged and nonpolar molecules, with distinctive properties due to delocalized electrons in their aromatic rings. Naturally, they are found in coal and in oil deposits and are also produced by the incomplete thermal decomposition of organic matter.

Therefore, the correct option is (a) Polycyclic aromatic hydrocarbons.

Note: -PAH compounds affect our food as well therefore it is important to prevent its consumption by taking measures such as the presence of filters on smoking equipment enables to decrease PAHs. Also avoid packing food items in high density polythene bags as they increase the PAH level in them.