Which diagram best represents the relationship between masses of subatomic particles? A proton + C electron proton + neutron B D proton neutron electron electron +
The Correct Answer and Explanation is:
The correct answer is C.
Explanation
To determine which diagram best represents the relationship between the masses of subatomic particles, we must compare the known masses of the proton, neutron, and electron.
Relative Masses of Subatomic Particles:
- Proton (p⁺): A proton has a relative mass of approximately 1 atomic mass unit (amu). Its actual mass is about 1.6726 x 10⁻²⁷ kg.
- Neutron (n⁰): A neutron also has a relative mass of approximately 1 amu. Its actual mass is about 1.6749 x 10⁻²⁷ kg.
- Electron (e⁻): An electron has a much smaller mass, approximately 1/1836th of a proton’s mass. Its actual mass is about 9.109 x 10⁻³¹ kg.
Analyzing the Diagrams:
The diagrams use a balance scale to visually compare the masses of two particles. The side of the scale that is lower holds the particle with the greater mass.
- Diagram A: This diagram shows a proton and an electron in balance, suggesting they have equal mass. This is incorrect. A proton is vastly more massive than an electron.
- Diagram B: This diagram shows the proton’s side is lower than the electron’s side, indicating that a proton is more massive than an electron. This statement is correct.
- Diagram D: This diagram shows the neutron’s side is lower than the electron’s side, indicating that a neutron is more massive than an electron. This statement is also correct.
- Diagram C: This diagram shows the neutron’s side is lower than the proton’s side. This indicates that a neutron is more massive than a proton. Comparing their precise masses (1.6749 x 10⁻²⁷ kg for a neutron vs. 1.6726 x 10⁻²⁷ kg for a proton), we see that the neutron is indeed slightly heavier. This statement is correct.
Why C is the Best Representation:
While diagrams B, C, and D all depict factually correct relationships, the question asks for the best representation. In chemistry and physics, the masses of the proton and neutron are often approximated as being equal (1 amu) because their masses are very close. However, they are not identical.
Diagram C illustrates the subtle but important difference in mass between a neutron and a proton. Choosing this option demonstrates a more precise understanding of particle physics than simply knowing that protons and neutrons are much heavier than electrons (as shown in B and D). The fact that a neutron is slightly heavier than a proton is a key detail that distinguishes them. Therefore, diagram C provides the most nuanced and specific correct relationship among the choices presented.
