WAEC Chemistry 2020 Objective — Question 7
Question 7 of 50 from the West African Examinations Council (WAEC) Chemistry 2020 Objective paper, with the correct answer and a full explanation.
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Equal masses of calcium trioxocarbonate (IV) were added to dilute hydrochloric acid at the temperature specified. Under which of the following conditions would the reaction be slowest?
- A. Calcium trioxocarbonate (IV) chips at 20 CCorrect
- B. Calcium trioxocarbonate (IV) chips at 40 C
- C. Calcium trioxocarbonate (IV) powder at 20 C
- D. Calcium trioxocarbonate (IV) powder at 40 C
Explanation
The reaction will be faster with marble powder than with marble chips since the former affords greater surface area of contact. Reaction rates are also lower at lower temperatures. Thus, chips at 20 C (lower surface area, lower temperature) gives the slowest reaction.
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