Question detail
Which exam-check sentence would most directly answer a question about HT only?
Try the question, check the answer, then read the explanation to understand the curriculum point.
At a glance
MCQ
Type
practice
Style
Topic
Exothermic and endothermic reactions
Question
- A. HT only: correct Unit 4.5 answer for The energy change of reactions (HT only)
- B. Incorrect exam-check: gives a memorised phrase without subtopic detail
- C. Incorrect exam-check: omits the key Energy changes vocabulary
- D. Incorrect exam-check: answers a different objective from Exothermic and endothermic reactions
Answer
The correct option is HT only: correct Unit 4.5 answer for The energy change of reactions (HT only).
Explanation
The correct option is HT only: correct Unit 4.5 answer for The energy change of reactions (HT only). It directly supports the approved learning objective to (HT only) Distinguish bond energy calculations from reaction profile interpretation. This exam-check version keeps the answer anchored to The energy change of reactions (HT only) within Exothermic and endothermic reactions, and avoids mixing energy transfer, reaction profiles, activation energy, chemical cells, fuel cells, exothermic reactions and endothermic reactions unless the objective names them.
Common mistake
Confusing bond‑energy calculations with reaction‑profile interpretation
Students think that the shape of a reaction profile can be used to calculate the exact energy change of a reaction, or that the activation energy shown on the profile is the same as the bond energies used in calculations.
Explain that a reaction profile is a qualitative diagram showing the relative energies of reactants, transition state and products, and that it cannot provide numerical bond‑energy values. Bond‑energy calculations use tabulated average energies for specific bonds to determine the overall energy change, while a reaction profile only indicates whether a reaction is exothermic or endothermic and the relative size of the activation energy.
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