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UPSC CAPF 2024 Previous Year GK Questions with Answers

GK questions asked in UPSC CAPF 2024, with answers and explanations.

Previous Year Questions

Q1.Environment & EcologyAsked in: UPSC CAPF · CAPF 2024, Paper IEasy

Which one of the following statements correctly defines PM1 particles in air ?

  1. A.These are suspended particles of diameter more than 10 micron
  2. B.These are the particles that are filtered by the nose during respiration
  3. C.These are extremely fine particles of diameter less than 1 micron
  4. D.These are coarse particles that penetrate directly through the lungs into the bloodstream
Show answer
Correct answer: C. These are extremely fine particles of diameter less than 1 micron

Explanation

The correct answer is C, extremely fine particles of diameter less than 1 micron. The number after PM gives the upper size limit of the particles in micrometres.

Particulate matter is classed by aerodynamic diameter: PM10 is 10 micrometres or less, PM2.5 is 2.5 micrometres or less, and PM1 is 1 micrometre or less, about one-seventieth of a human hair's width. The smaller the particle, the deeper it travels: PM1 slips past the nose and throat, reaches the alveoli and can even pass into the blood, which is why it is linked with heart and lung disease. Such fine particles come mostly from vehicle exhaust, burning of fuel and crop residue, and industrial smoke.

A is wrong: particles larger than 10 micrometres are coarse dust, not PM1.

B is wrong: the nose traps mainly larger particles; PM1 is too fine to be filtered there.

D is wrong: PM1 is extremely fine, not coarse, and it is the fine particles, not coarse ones, that reach the bloodstream.

Exam tip: PM10 coarse, PM2.5 fine, PM1 ultra-fine; the smaller the number, the deeper it goes into the body.

Q2.Environment & EcologyAsked in: UPSC CAPF · CAPF 2024, Paper IMedium

Which one of the following statements with regard to greenhouse effect is correct?

  1. A.It can take place inside a glass chamber where no radiation can pass into it or pass back through it
  2. B.It can take place inside a glass chamber where long wavelength infrared radiation can pass through into it and short wavelength infrared radiation cannot pass back through it
  3. C.It can take place inside a glass chamber where short wavelength infrared radiation can pass through into it and long wavelength infrared radiation cannot pass back through it
  4. D.It can take place inside a glass chamber where all infrared radiation can pass into it or pass back through it
Show answer
Correct answer: C. It can take place inside a glass chamber where short wavelength infrared radiation can pass through into it and long wavelength infrared radiation cannot pass back through it

Explanation

The correct answer is C: the chamber lets short-wavelength radiation in but does not let long-wavelength infrared out, so heat is trapped.

Sunlight reaching a glasshouse is mostly visible light and short-wavelength (near) infrared, which glass transmits easily. The plants and soil inside absorb it, warm up and re-radiate the energy as long-wavelength infrared, because cooler bodies emit at longer wavelengths. Glass is largely opaque to this long-wave radiation, so the energy stays inside and the temperature rises. In the atmosphere, carbon dioxide, water vapour, methane and nitrous oxide play the role of the glass, keeping the Earth about 33 °C warmer than it would otherwise be.

A is wrong: if no radiation entered, there would be no energy to trap.

B is wrong: it reverses the wavelengths; long waves are the ones held back.

D is wrong: if all infrared could escape freely, nothing would be trapped and no warming would occur.

Exam tip: in short, out long; glass and greenhouse gases stop the outgoing long-wave infrared.

All UPSC previous year questions