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WAEC Chemistry 2011 Objective — Question 35

Question 35 of 50 from the West African Examinations Council (WAEC) Chemistry 2011 Objective paper, with the correct answer and a full explanation.

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What is the value of n in the following equation? CrO4²⁻+14H⁺+ne⁻→2Cr³⁺+7H2O

  • A. A. 2
  • B. B. 3
  • C. C. 6Correct
  • D. D. 7

Explanation

Equating overall charge on both sides: L.H.S. = -2+14-n = 12-n. R.H.S. = (2x+3)+(7x0) = +6. Equating: 12-n = 6, so n = 6.

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