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Topic Oxidation State
Asked 3 times across 3 UPSC exams over 8 years (2018–2026), peaking in 2018.
Key insights
- Most tested in CDS — 1 of 3 PYQs
- Most asked in 2018
- Recurs across 3 years (2018–2026)
How it travelled across exams
First appearance in each exam — the same idea, reframed.
CDS 2018 → NDA 2024 → CISF 2026
How the concept evolved
Rising — more than half its appearances (3 of 3) are since 2016.
Sample questions
You've seen the pattern — here are a few of the actual PYQs.
CISF2026
The oxidation state of Chromium is the same in all of the following compounds except one. CrO3, Cr2O3, CrCl3, Cr2(CO3)3 Select the compound whose oxidation state is different from others?
- A CrO3
- B Cr2O3
- C CrCl3
- D Cr2(CO3)3
Answer key not yet available (pending official release)
Science & Technology › Physics & Chemistry
NDA2024
What is the oxidation state of Vanadium in V2O5?
- A +2
- B +4
- C +3
- D +5 ✓
✓ Correct answer: (D)
Science & Technology › Physics & Chemistry
CDS2018
Which one of the following nitrogen oxides has the highest oxidation state of nitrogen?
- A NO
- B NO2
- C N2O
- D N2O5 ✓
✓ Correct answer: (D)
Science & Technology › Physics & Chemistry
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