Previous Year Question
Magnetite particles, suspected to cause neurodegenerative problems, are generated as environmental pollutants from which of the following?
Brakes of motor vehicles
Engines of motor vehicles
Microwave stoves within homes
Power plants
Telephone lines
Select the correct answer using the codes given below.
1, 2, 3 and 5
1, 2 and 4
3, 4 and 5
1, 2, 3, 4 and 5
Correct Answer: B
Detailed Solution
Magnetite is a magnetic oxide of iron with the chemical formula Fe₃O₄.
Ultrafine magnetite particles can be generated by high-temperature combustion and the friction of metals.
In motor vehicles, friction between brake pads and discs during braking produces iron-rich dust.
Friction and high temperatures can form minute magnetite particles in this dust. Therefore, source 1 is correct.
Fuel combustion in motor-vehicle engines and the metal-bearing components of engines may also generate magnetite particles.
These particles can enter the atmosphere with vehicle exhaust. Therefore, source 2 is correct.
Magnetite particles may also occur in fly ash and emissions from power plants burning coal and other fossil fuels. Therefore, source 4 is correct.
Microwave stoves used in homes are not normal environmental sources of magnetite particles. Therefore, source 3 is not correct.
Telephone lines are also not normal pollution sources producing magnetite particles. Therefore, source 5 is not correct.
Extremely small magnetite particles can enter the body through inhalation.
Such particles have the potential to reach the brain through the olfactory-nerve pathway or blood circulation.
Magnetite particles reaching the brain from external sources may contribute to oxidative stress and cellular damage.
Their possible association with neurodegenerative problems such as Alzheimer’s disease is under study; the term ‘suspected’ does not mean that direct causation has been established in every case.
Magnetite may also form in the body through natural and biological processes, but the question concerns environmental particles generated by human activities.