Question detail

Which comparison keeps HT only separate from a nearby Unit 4.5 idea?

Try the question, check the answer, then read the explanation to understand the curriculum point.

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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 comparison: says the two nearby ideas mean the same thing
C. Incorrect comparison: uses the same evidence for exothermic and endothermic cases
D. Incorrect comparison: ignores the direction of energy transfer

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 comparison 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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For The energy change of reactions (HT only), which answer best supports this AQA GCSE Chemistry Unit 4.5 objective: (HT only) Distinguish bond energy calculations from reaction profile interpretation?