Final answer:
Energy and mass are interconvertible as described by E = mc². During atom formation, energy released from mass conversion leads to a measurable decrease in mass. Thus, the correct answer to the student's question is B) Energy is released, so the mass is reduced.
Step-by-step explanation:
The connection between energy and mass during the formation of an atom is described by Albert Einstein's famous equation, E = mc². When an atom forms, energy is often released, particularly in nuclear reactions where the mass of the products is usually less than the mass of the reactants due to a portion of the mass being converted into energy. This process reflects the conservation of energy and the interconvertibility of mass and energy. Hence, in the context of atom formation, a common scenario would be energy being released as a result of mass being converted into energy (B).
For chemical reactions, however, the changes in mass are minuscule and usually not observable. It's worth noting that in nuclear reactions such as fusion and fission, the measurable decrease in mass corresponds to the significant amount of energy released, again following Einstein's equation. In essence, according to modern physics, mass and energy are two forms of the same thing and can be converted into each other, with energy absorbing reactions leading to an increase in mass and energy releasing reactions leading to a reduction in mass.