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Topic Water treatment
Asked 4 times across 2 UPSC exams over 45 years (1980–2025), peaking in 2025.
Key insights
- Most tested in CSE — 3 of 4 PYQs
- Most asked in 2025
- Recurs across 4 years (1980–2025)
How it travelled across exams
First appearance in each exam — the same idea, reframed.
CSE 1980 → CDS 2014
How the concept evolved
Long-running — most appearances (3 of 4) predate 2016, and it still returns.
Related concepts
Ideas UPSC tests alongside this one — keep exploring.
Sample questions
You've seen the pattern — here are a few of the actual PYQs.
CSE2025
Consider the following statements
Statement IActivated carbon is a good and an attractive tool to remove pollutants from effluent streams and to remediate contaminants from various industries
Statement IIActivated carbon exhibits a large surface area and a strong potential for adsorbing heavy metals
Statement IIIActivated carbon can be easily synthesized from environmental wastes with high carbon content
Which one of the following is correct in respect of the above statements?
- A Both Statement II and Statement III are correct and both of them explain Statement I ✓
- B Both Statement II and Statement III are correct but only one of them explains Statement I
- C Only one of the Statements II and III is correct and that explains Statement I
- D Neither Statement II nor Statement III is correct
✓ Correct answer: (A)
Science & Technology › Physics & Chemistry
CDS2014
Which method of water purification does not kill microorganism?
- A Boiling
- B Filtration ✓
- C Chlorination
- D UV-irradiation
✓ Correct answer: (B)
Science & Technology › Biology & Health
CSE2012
What is the role of ultraviolet (UV) radiation in the water purification systems?
- It inactivates/kills the harmful microorganisms in water
- It removes all the undesirable odours from the water
- It quickens the sedimentation of solid particles, removes turbidity and improves the clarity of water
Which of the statements given above is/are correct?
- A 1 only ✓
- B 2 and 3 only
- C 1 and 3 only
- D 1, 2 and 3
✓ Correct answer: (A)
Science & Technology › Physics & Chemistry
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