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JAMB Chemistry 1984 Question 36

Question 36

Electrolysis

If the cost of electricity required to deposit 1 g of magnesium is N5.00, how much would it cost to deposit 10g of aluminium? (Relative atomic masses: Al = 27, Mg = 24)

  1. A.N10.00
  2. B.N27.00
  3. C.N44.44
  4. D.N66.67
  5. E.N33.33.
Show the answer and explanation

Answer: D (N66.67)

Explanation

1 g of Mg (Mg2+) needs 2/24 = 0.0833 F. 10 g of Al (Al3+) needs 3 × 10/27 = 1.111 F, which is 13.33 times as much, so the cost is 13.33 × N5.00 = N66.67.