One of the features of the fission process is that

Analyze the question: We're asked to identify a feature of nuclear fission, the splitting of a heavy nucleus (like Uranium-235) into smaller nuclei.

Explain the concept: In fission, a slow neutron strikes a heavy nucleus such as U-235:

U-235 + n → Ba-141 + Kr-92 + 3n + energy

Key features:

• The nucleus splits into two lighter nuclei (fission fragments).
• Several neutrons (2 or 3) are released.
• A large amount of energy is released, because some mass is converted to energy (E = mc²).
• The released neutrons can strike other U-235 nuclei, causing more fissions. This is a chain reaction.

Check each option:

• A. It leads to chain reaction. Correct. The neutrons released go on to split other nuclei, sustaining the reaction.
• B. Its products are not radioactive. Wrong. Fission fragments such as Ba-141 and Kr-92 are highly radioactive, which is why nuclear waste is a problem.
• C. Neutrons are not released. Wrong. Neutrons are released, and this is what makes the chain reaction possible.
• D. The sum of the masses of the reactants equals the sum of the masses of the products. Wrong. There is a mass defect: the products have slightly less mass than the reactants, and the missing mass is released as energy.

Answer: Option A.

Exam tip: Remember fission as "Split → Several neutrons → Self-sustaining chain reaction." Whenever you see an option saying "neutrons are not released," "products are stable," or "mass is conserved exactly" for fission, eliminate it. Mass is not conserved in nuclear reactions, since some is converted to energy.