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Topic Stoichiometry
Asked 7 times across 3 UPSC exams over 8 years (2018–2026), peaking in 2018.
Key insights
- Most tested in CDS — 5 of 7 PYQs
- Most asked in 2018
- Recurs across 5 years (2018–2026)
How it travelled across exams
First appearance in each exam — the same idea, reframed.
CDS 2018 → EPFO 2020 → ESE 2026
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.
ESE2026
1 kg of Hydrogen fuel burns with 8 kg of oxygen to give the product as
- A 9 kg of hydrogen peroxide
- B 9 kg of water
- C 18 kg of hydrogen peroxide
- D 18 kg of water
Answer key not yet available (pending official release)
Engineering › Engineering Mathematics & General
CDS2023
Which one of the following equations is the balanced equation for the given reaction ? Fe + H2O → Fe3O4 + H2
- A Fe + 4H2O → Fe3O4 + H2
- B 3Fe + H2O → Fe3O4 + 2H2
- C 3Fe + 4H2O → Fe3O4 + 4H2 ✓
- D 3Fe + 4H2O → Fe3O4 + H2
✓ Correct answer: (C)
Science & Technology › Physics & Chemistry
CDS2022
The number of moles of oxygen gas used in the complete combustion of 1 mole of glucose is :
- A 1
- B 3
- C 6 ✓
- D 12
✓ Correct answer: (C)
Science & Technology › Physics & Chemistry
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