Which of the following statements is true of nuclear fission?

Step 1: Analyze the question We are asked which statement is true of nuclear fission.

Step 2: The concept Nuclear fission is the splitting of a heavy nucleus (e.g. Uranium-235) into two smaller nuclei after it absorbs a slow-moving neutron. It also releases 2-3 neutrons and a large amount of energy.

Example: ²³⁵U + ¹n → ¹⁴¹Ba + ⁹²Kr + 3 ¹n + energy

The energy comes from the mass defect: the total mass of the products is slightly less than the mass of the original nucleus plus the neutron. This lost mass is converted to energy according to Einstein's equation:

E = Δm c²

Step 3: Check each option

• A. Heavy nuclei combine to form new element. False. Heavy nuclei split in fission. Combining is fusion.
• B. Protons are used in bombarding heavy nucleus. False. Neutrons are used, because they carry no charge and so are not repelled by the positively charged nucleus.
• C. The sum of the masses of the products is greater than the mass of the original substance. False. The products have less mass (mass defect), and this is why energy is released.
• D. Two light nuclei combine to form a heavy nucleus. False. This describes nuclear fusion.
• E. Very large amount of energy is released. True. Fission releases an enormous amount of energy, which is the principle behind nuclear power plants and atomic bombs.

Step 4: Answer

Tip: Remember "FISsion = Split" and "FUsion = FUse (join)". For fission, think: heavy nucleus + neutron, then splits, then products have less mass and energy is released. Also, in NECO and JAMB, the bombarding particle in fission is always the neutron, never the proton.