Question

Which statements describe nuclear reactions? Check all that apply.

Nuclear reactions involve the nuclei of atoms.
Nuclear reactions involve the electrons of atoms.
The products of nuclear reactions are lighter than the reactants.
The products of nuclear reactions are heavier than the reactants.
Fission produces energy, while fusion requires energy.

Answer 1

Only the first statement is correct:

- Nuclear reactions involve the nuclei of atoms. — True.

Why the others are incorrect or incomplete:
- Nuclear reactions involve the electrons of atoms. — False. Electrons participate in chemical (atomic) reactions; nuclear reactions change protons/neutrons in the nucleus (though beta decay emits electrons).
- The products of nuclear reactions are lighter than the reactants. — Not always. This is true for fission, but not for fusion.
- The products of nuclear reactions are heavier than the reactants. — Not always. This is true for fusion, but not for fission.
- Fission produces energy, while fusion requires energy. — False/misleading. Typical fission of heavy nuclei and fusion of light nuclei both release energy overall; fusion does require a high initial input to overcome the Coulomb barrier but can be net-energy-releasing.