UPSC Prelims 2021 · GS Paper I
Question 25: Environment and Ecology
Magnetite particles, suspected to cause neurodegenerative problems, are generated as environmental pollutants from which of the following?
- 1.Brakes of motor vehicles
- 2.Engines of motor vehicles
- 3.Microwave stoves within homes
- 4.Power plants
- 5.Telephone lines
Select the correct answer using the code given below.
AnswerUPSC’s answer is (b).
Magnetite nanoparticles found in human brain tissue have been traced to air pollution from combustion and friction. Brake wear on motor vehicles, engine exhaust and power plants release fine magnetite particles. Microwave stoves and telephone lines give off electromagnetic radiation but do not generate magnetite particles. Remember: magnetite pollution comes from friction and combustion sources.
- 1. Brake wear releases magnetite particles.
- 2. Engine combustion produces magnetite-bearing fine particles.
- 3. Microwave stoves emit radiation, not magnetite particles.
- 4. Power plants release magnetite particles in fly ash and emissions.
- 5. Telephone lines are not a source of magnetite particles.
How you could have got this
- If you were sure statement 3 is not correct, (a), (c) and (d) go: each of them includes 3.
What you needed to know: Microwave stoves emit radiation, not magnetite particles.
Only (b) is left. You didn’t need statements 1, 2, 4 or 5.
Which options go is worked out from UPSC’s key and the options, not by a model.
Why each option is right or wrong
- (a) Wrong: microwave stoves and telephone lines do not emit magnetite particles.
- (b) Right: brakes, engines and power plants generate magnetite particles.
- (c) Wrong: microwaves and telephone lines are not sources, and it omits brakes and engines.
- (d) Wrong: it wrongly includes microwave stoves and telephone lines.
Answer: UPSC’s key. Explanation: written by UPSC Grade, not by UPSC.
Source: UPSC, Civil Services (Preliminary) Examination 2021, General Studies Paper I, Series A. The paper on upsc.gov.in.