Question

Assertion: Air pollutants are either gaseous or particulate.

Reason: Catalytic converters greatly reduce emission from diesel vehicle.

• A. Both the assertion and reason are true and the reason is the correct explanation of the assertion
• B. Both the assertion and reason are true but the reason is not the correct explanation of the assertion
• C. Assertion is true but the reason is false
• D. Both the assertion and reason are false

Answer 1

The correct option is B Both the assertion and reason are true but the reason is not the correct explanation of the assertion

Any undesirable change in the quality of air is defined as air pollution. Pollution is caused by the addition of some undesirable agents into the air, known as pollutants.
Based on their physical nature, air pollutants can be -

• Gaseous such as oxides of nitrogen (e.g. NO₂), oxides of sulphur (SO₂, SO₃), carbon monoxide (CO), carbon dioxide (CO₂), organic chemicals (hydrocarbons, volatile organic compounds or VOCs), water vapour etc.
• Particulate matter such as dust, soot (unburnt carbon particles released as a result of incomplete combustion of hydrocarbons or fossil fuels) etc.

Catalytic converter is a device that converts toxic gases into less-toxic pollutants by redox reaction. It is composed of a metal housing with a ceramic honeycomb-like interior with insulating layers. This honeycomb interior has thin wall channels that are coated with a wash coat of aluminium oxide. This coating is porous and increases the surface area, allowing more reactions to take place and containing precious metals such as platinum, rhodium, and palladium. Thus, both the assertion and reason are true but the reason is not the correct explanation of the assertion.