WAEC Chemistry 2021 Objective — Question 30
Question 30 of 50 from the West African Examinations Council (WAEC) Chemistry 2021 Objective paper, with the correct answer and a full explanation.
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30. At 25°C, evaporation of a 100cm³ solution of K2CO3 to dryness gave 14g of the salt. What is the solubility of K2CO3 at 25°C? [K2CO3=138]
- A. 0.01 mol dm⁻³
- B. 0.101 mol dm⁻³
- C. 1.01 mol dm⁻³Correct
- D. 10.0 mol dm⁻³
Explanation
Moles of K2CO3 = 14/138 = 0.1014 mol. Volume = 0.1 dm³. Solubility = 0.1014/0.1 = 1.014 mol dm⁻³ ≈ 1.01 mol dm⁻³.
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