Why is the total mass of all individual protons and neutrons in a nucleus greater than the mass of the nucleus which they constitute?
Correct answer: D. When protons and neutrons combine to form a nucleus, some mass is converted into energy, resulting in mass loss.
- A. When protons and neutrons combine to form a nucleus, the mass decreases because energy is gained.
- B. The apparent mass loss is due to inaccuracies in measuring the mass of the nucleus.
- C. This statement is not true in most cases.
- D. When protons and neutrons combine to form a nucleus, some mass is converted into energy, resulting in mass loss.
Explanation
The correct answer is that when protons and neutrons combine to form a nucleus, some mass is converted into energy, leading to a mass defect. This is explained by Einstein's mass-energy equivalence principle (E=mc²), where 'm' is the mass converted into energy, and 'c' is the speed of light. The energy released during this process binds the nucleons together, making the nucleus more stable.Option A is incorrect because it suggests energy is gained, whereas energy is actually released. Option B is incorrect because it inaccurately attributes mass loss to measurement error, ignoring the physical reality of mass defect. Option C is incorrect because it dismisses the statement without basis, despite the mass defect being a fundamental concept in nuclear physics.
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Atomic nuclei contain protons and neutrons, with nuclear size, mass defect and binding energy describing their stability. The work covers alpha, beta and gamma decay, decay equations, half-life and decay rate, along with radiation safety and medical applications such as imaging, radiotherapy and tracers.
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