In beta-minus decay, the Q-value of the process is E. Which of the following statements are correct?

The kinetic energy of the emitted beta particle cannot exceed E.
The kinetic energy of the antineutrino emitted can range from zero to E.
The neutron-to-proton ratio (N/Z) of the daughter nucleus is altered compared to the parent.
The beta particle is emitted from the nucleus with a fixed kinetic energy equal to E.

Correct answer: The kinetic energy of the emitted beta particle cannot exceed E.

Solution

In beta-minus decay, a neutron converts to a proton, decreasing the N/Z ratio. The Q-value E is shared between the beta particle and the antineutrino (recoil is negligible), so neither can individually exceed E. Thus statements A and C are correct; B is also correct since the antineutrino KE ranges from 0 to E.

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