Which statement BEST describes a nuclear fusion reaction?
Mass and Elements Produced by Stars
Information in the chart shown below suggests a relationship between the mass of a star and the elements that can be produced by a star.
Examples of Elements Produced
Low-Mass Star High-Mass Star
helium helium
lithium lithium
carbon carbon
nitrogen
oxygen
sodium
magnesium
silicon
iron
A. The total number of protons and neutrons is conserved.
B. The amount of matter is conserved.
C. The total number of atoms is conserved.
D. The total number of electrons and neutrons is conserved.
Answer (2)
Nuclear fusion is the process where light atomic nuclei combine, conserving the total number of protons and neutrons. Therefore, the best answer is Option A .
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Nuclear fusion combines atomic nuclei, releasing energy.
Mass is not conserved, as it's converted into energy ( E = m c 2 ).
The number of protons and neutrons is conserved.
Therefore, the best description is that the total number of protons and neutrons is conserved. A
Explanation
Understanding the Question We are asked to identify the statement that best describes a nuclear fusion reaction, considering the provided table of elements produced by stars of different masses.
Key Concepts Nuclear fusion is a process where multiple atomic nuclei combine to form a heavier nucleus. This process is responsible for the energy production in stars. During fusion, mass is converted into energy, as described by Einstein's famous equation, E = m c 2 . This means that the amount of matter is not conserved.
Analyzing the Options Let's analyze the given options:
Option A: The total number of protons and neutrons is conserved. In nuclear reactions, the number of nucleons (protons and neutrons) is conserved, although they may rearrange.
Option B: The amount of matter is conserved. This is incorrect because mass is converted into energy during nuclear fusion.
Option C: The total number of atoms is conserved. This is incorrect because atoms are transformed into different atoms during fusion.
Option D: The total number of electrons and neutrons is conserved. The number of electrons is not necessarily conserved.
Conclusion Based on the analysis, the statement that best describes a nuclear fusion reaction is that the total number of protons and neutrons is conserved.
Examples
Nuclear fusion is the energy source of stars, including our Sun. It combines lighter elements, like hydrogen, into heavier ones, like helium, releasing vast amounts of energy in the process. This energy sustains life on Earth. Understanding nuclear fusion helps us explore potential clean energy sources and the life cycle of stars.
