Vanadium and chromium redox chemistry Quiz
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5 questions, one answer each
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1. What is the colour of the VO²⁺ ion?
- A. Yellow
- B. Blue
- C. Green
- D. Violet
2. Which reagent can reduce V³⁺ (E° −0.26 V) to V²⁺?
- A. Fe²⁺ (Fe³⁺/Fe²⁺ +0.77 V)
- B. Sn²⁺ (Sn⁴⁺/Sn²⁺ +0.15 V)
- C. Hydrogen (0.00 V)
- D. Zinc (Zn²⁺/Zn −0.76 V)
3. What is seen when sodium hydroxide is added to orange dichromate(VI) solution?
- A. It turns yellow
- B. It turns green
- C. It turns blue
- D. No change
4. What is the oxidation number of chromium in CrO₄²⁻?
- A. +3
- B. +4
- C. +6
- D. +8
5. Which conditions oxidise Cr³⁺ to CrO₄²⁻?
- A. Zinc in acid
- B. Hydrogen peroxide in alkaline conditions
- C. Dilute hydrochloric acid
- D. Iron(II) ions in acid