When a uranium nucleus splits, does the sum of the masses of the products become less than the mass of the original nucleus?

When a uranium nucleus undergoes fission, it splits into smaller nuclei (the fission products) along with a release of neutrons and energy. The key point is that during this process, a small amount of the mass of the original nucleus is converted into energy, as per Einstein's mass-energy equivalence principle, E=mc².

This conversion explains why the total mass of the resulting products is indeed less than the mass of the original uranium nucleus. The difference in mass, known as the "mass defect," is directly related to the energy released during the fission process. Therefore, the correct answer to the question is true; the sum of the masses of the products becomes less than the mass of the original uranium nucleus due to the conversion of some mass into energy.