JEE Main 2023 — Environmental Chemistry Question with Solution

Option A, By using catalytic converters in the automobiles/industry, is the most appropriate answer to control photochemical smog.

Photochemical smog is a type of air pollution that forms in urban areas when pollutants from automobile and industrial emissions, such as nitrogen oxides (NOx) and volatile organic compounds (VOCs), react in the presence of sunlight.

Catalytic converters are devices that are installed in the exhaust systems of automobiles and in some industrial processes to remove pollutants from exhaust gases. They work by using a catalyst to convert harmful pollutants, such as NOx and VOCs, into less harmful substances before they are released into the atmosphere. This can significantly reduce the formation of photochemical smog.

Option B, By complete combustion of fuel, is not a complete or sufficient solution to control photochemical smog. Complete combustion of fuel, which refers to the complete oxidation of the fuel to produce carbon dioxide and water, can reduce the amount of unburned hydrocarbons and carbon monoxide in the exhaust gases.

However, even with complete combustion, other pollutants, such as nitrogen oxides (NOx), can still be produced and contribute to the formation of photochemical smog. NOx emissions are a result of high temperatures and pressures in the combustion process and are not easily prevented through complete combustion alone.

Additionally, while complete combustion can reduce the amount of certain pollutants, it does not address other sources of pollution, such as industrial emissions, that can contribute to the formation of photochemical smog.

Therefore, while complete combustion can be an important step in reducing emissions and controlling photochemical smog, it is not a sufficient solution on its own and must be combined with other methods, such as the use of catalytic converters, to effectively address this issue.

Option C, using tall chimneys, is not a direct way to control photochemical smog. Tall chimneys can help to disperse pollutants into the atmosphere, but do not necessarily prevent their formation in the first place.

Option D, By using a catalyst, is not a complete or sufficient solution to control photochemical smog. While catalysts can be used to convert harmful pollutants into less harmful substances, they need to be part of a larger system, such as a catalytic converter, to effectively reduce emissions.

Using a catalyst alone, without the proper design, engineering, and installation, is unlikely to be effective in controlling photochemical smog. It is important to note that the goal is to reduce the overall emissions of pollutants, such as nitrogen oxides (NOx) and volatile organic compounds (VOCs), which are the precursors to photochemical smog.

Therefore, while catalysts can be a useful tool in controlling photochemical smog, they must be used in combination with other methods, such as the use of catalytic converters in automobiles and industry, to be most effective.