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WAEC Chemistry 2023 Objective — Question 32

Question 32 of 50 from the West African Examinations Council (WAEC) Chemistry 2023 Objective paper, with the correct answer and a full explanation.

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How many grammes of NaOH(s) would be needed to produce 100.0 cm3 of a 0.20 mol dm⁻³ NaOH(aq)? [NaOH=40.0]

  • A. 0.02 g
  • B. 0.80 gCorrect
  • C. 20.0 g
  • D. 800.0 g

Explanation

Volume = 100 cm3 = 0.1 dm3. Mole of NaOH = 0.20 mol dm⁻³ × 0.1 dm3 = 0.02 mol. Mass = 0.02 mol × 40 g/mol = 0.80 g.

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