WAEC Chemistry 2022 Objective — Question 30
Question 30 of 50 from the West African Examinations Council (WAEC) Chemistry 2022 Objective paper, with the correct answer and a full explanation.
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If 50 cm³ of a saturated solution of KNO3 at 40°C contained 5.05g of the salt, its solubility at the same temperature would be [KNO3 = 101]
- A. 1.0 mol dm⁻³Correct
- B. 1.5 mol dm⁻³
- C. 2.0 mol dm⁻³
- D. 5.0 mol dm⁻³
Explanation
Moles of KNO3 = 5.05g ÷ 101 g/mol = 0.05 mol. Volume = 50cm³ = 0.05dm³. Solubility = 0.05mol ÷ 0.05dm³ = 1.0 mol dm⁻³.
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