WAEC Chemistry 2024 Objective — Question 5
Question 5 of 50 from the West African Examinations Council (WAEC) Chemistry 2024 Objective paper, with the correct answer and a full explanation.
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5. The oxidation number of chromium in Na₂Cr₂O₇ is
- A. +2
- B. +6Correct
- C. +7
- D. +12
Explanation
For Na (+1) and O (-2): 2(+1)+2Cr+7(-2)=0 → 2+2Cr-14=0 → Cr=+6.
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