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Topic Chemical Reactions
Asked 7 times across 4 UPSC exams over 7 years (2018–2025), peaking in 2018.
Key insights
- Most tested in CDS — 3 of 7 PYQs
- Most asked in 2018
- Recurs across 4 years (2018–2025)
How it travelled across exams
First appearance in each exam — the same idea, reframed.
CDS 2018 → CISF 2021 → NDA 2023 → CAPF 2025
How the concept evolved
Rising — more than half its appearances (7 of 7) 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.
CAPF2025
Match List-I with List-II and select the answer using the code given below the Lists
| List I (Reaction) | List II (Type of Reaction) |
|---|
| A. CH4 + 2O2 → CO2 + 2H2O + heat and light | 1. Combustion |
| B. Mg + H2SO4 → MgSO4 + H2 | 2. Double displacement |
| C. 2NaOH + H2SO4 → Na2SO4 + 2H2O | 3. Displacement |
| D. NaCl + AgNO3 → NaNO3 + AgCl | 4. Neutralisation |
Codes:
- A A-1 B-3 C-4 D-2
- B A-1 B-4 C-3 D-2
- C A-2 B-3 C-4 D-1
- D A-2 B-4 C-3 D-1
Answer key not yet available (pending official release)
Science & Technology › Physics & Chemistry
NDA2023
An iron nail dipped in copper sulphate solution turns brown. This is due to which one of the following types of reactions?
- A Addition reaction
- B Decomposition reaction
- C Substitution reaction
- D Displacement reaction ✓
✓ Correct answer: (D)
Science & Technology › Physics & Chemistry
NDA2023
Airbags work on the principle of a chemical reaction triggered by the impact producing a gaseous product that causes a sudden volume change. Which one among the following chemical conversions is responsible for this?
- A Sodium azide into nitrogen gas ✓
- B Solid carbon dioxide into gaseous carbon dioxide
- C Carbon dioxide into carbon monoxide
- D Sudden conversion of gaseous carbon dioxide into carbon monoxide
✓ Correct answer: (A)
Science & Technology › Physics & Chemistry
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