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    Question

    Consider the following three nuclear reactions:

    Which of these is/are accompanied by the maximum energy per nucleon released ?
    A I only Correct Answer Incorrect Answer
    B III only Correct Answer Incorrect Answer
    C II only Correct Answer Incorrect Answer
    D I and III Correct Answer Incorrect Answer

    Solution

    In nuclear reactions, the energy released per nucleon depends on how much the binding energy per nucleon increases during the process. Let’s analyze the three processes using this concept: The binding energy per nucleon curve peaks around iron (Fe, A ≈ 56), which is the most stable nucleus. The energy per nucleon released in any nuclear reaction depends on how far the product nuclei move towards iron on this curve. • Heavy nuclei like uranium have lower binding energy per nucleon . • When uranium-235 undergoes fission, it splits into medium-mass nuclei (e.g., barium and krypton), which are closer to iron , thus releasing energy. • Energy per nucleon released is moderate , typically about 0.8 MeV per nucleon. II. Fusion of two deuterons • Light nuclei like deuterium (²H) have very low binding energy per nucleon. • Fusion to form helium or heavier light elements significantly increases the binding energy per nucleon. • This process releases the highest energy per nucleon , often up to 6–7 MeV per nucleon in some reactions • This is a slow and less energetic process , where uranium-238 emits a helium nucleus (alpha particle). • The energy released is small , usually a few MeV total , not significant per nucleon compared to fission or fusion. Among the three, fusion of deuterons releases the maximum energy per nucleon , as it moves light nuclei significantly up the binding energy curve.

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