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Topic Acids and bases
Asked 18 times across 5 UPSC exams over 42 years (1984–2026), peaking in 2021.
Key insights
- Most tested in CDS — 13 of 18 PYQs
- Most asked in 2021
- Recurs across 11 years (1984–2026)
How it travelled across exams
First appearance in each exam — the same idea, reframed.
CSE 1984 → CDS 2014 → EPFO 2020 → NDA 2023 → CISF 2024
How the concept evolved
184
214
117
118
220
321
222
223
124
225
126
Rising — more than half its appearances (15 of 18) are since 2016.
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.
CDS2026
Consider the following statements regarding bases and alkalis
- All bases dissolve in water
- Bases which are soluble in water are called alkalis
- An alkali is soapy to touch, bitter and corrosive
- Addition of water to an alkali generates heat
Which of the statements given above are correct ?
- A 1, 2, 3 and 4
- B 2, 3 and 4 only ✓
- C 1 and 2 only
- D 3 and 4 only
✓ Correct answer: (B)
Science & Technology › Physics & Chemistry
CDS2025
Which one of the following contains all Lewis acids ?
- A AlCl₃, Co²⁺, BF₃ ✓
- B BCl₃, NH₃, OH⁻
- C Mg²⁺, H₂O, F⁻
- D BF₃, NH₃, H₂O
✓ Correct answer: (A)
Science & Technology › Physics & Chemistry
CDS2025
A solution with a pH value less than 7 is a/an :
- A Neutral solution
- B Basic solution
- C Acidic solution
- D Hypotonic solution
Answer key not yet available (pending official release)
Science & Technology › Physics & Chemistry
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