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JAMB Chemistry 1998 Question 29

Question 29

Energy Changes

In the diagram above, the activation energy for the backward reaction is

Diagram for this question
  1. A.+5kJ
  2. B.+15kJ
  3. C.+25kJ
  4. D.+30kJ
Show the answer and explanation

Answer: C (+25kJ)

Explanation

The backward reaction starts from the products (2PQ, about 15 kJ on the graph) and must climb to the top of the peak (40 kJ). So its activation energy is about 40 − 15 = 25 kJ.