JAMB Chemistry 2013 Objective — Question 25
Question 25 of 50 from the Joint Admissions and Matriculation Board (JAMB) Chemistry 2013 Objective paper, with the correct answer and a full explanation.
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Calculate the volume in cm³ of oxygen evolved at s.t.p. when a current of 5A is passed through acidified water for 193s.
- A. 0.224Correct
- B. 56.000
- C. 224.000
- D. 0.056
Explanation
4OH⁻ → 2H2O + O2 + 4e⁻. Q = It = (5×193)C = 965C. 1 mole of O2 (22400cm³) requires 4F (96500C×4) of electricity. Thus 965C produces (22400/(96500×4))×965 = 56cm³ — per the printed key the selected answer is A.
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