The main industrial source of emission of hydrogen sulphide air pollutant is

Solution (By Examveda Team)

A) Petroleum Refineries: Petroleum (crude oil) naturally contains sulfur compounds.
During the refining process, these sulfur compounds are converted into hydrogen sulfide (H₂S).
Refineries then need to remove this H₂S to produce cleaner fuels.
This removal process, if not properly controlled, releases H₂S into the air.
Therefore, petroleum refineries are a significant and well-known source of H₂S emissions.

B) Coal-based Thermal Power Plants: Coal also contains sulfur, and burning it releases sulfur dioxide (SO₂), primarily, not H₂S.
While some very small amounts of H₂S *might* be present, it's not the primary sulfur-containing air pollutant from coal power plants.

C) Pulp and Paper Plants: These plants can release various sulfur compounds, including methyl mercaptan and dimethyl sulfide, especially during the pulping process.
However, H₂S isn't usually the *main* sulfur-containing air pollutant released, although it can be present in smaller quantities.

D) Metallurgical Roasting & Smelting Plant: These processes deal with metal ores.
If the ores contain sulfur, roasting and smelting primarily produce sulfur dioxide (SO₂).
Again, while trace amounts of H₂S could be formed, it's not the dominant sulfur emission.

In summary: While all options *can* potentially release some H₂S, petroleum refineries are the *major* industrial source because of the sulfur content inherent in crude oil and the H₂S formation during refining.