How can a nucleus be described by particular values of A, Z and N when the mass of the nucleus is not equal to Zm_p + Nm_n, where m_p and m_n are the masses of free protons and neutrons? A) A, Z and N have no intrinsic meaning. B) A, Z and N describe the number of particles of given types, but mass has no meaning when part of the mass is elsewhere in the universe. C) A, Z and N describe the number of particles an ideal rather than a real nucleus would have. D) A, Z and N describe the number of particles of given types in the nucleus, but not their masses in a bound state. E) A, Z and N describe the number of particles of given types in the nucleus since the missing mass consists of electrons that are also present in the nucleus.

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Quizplus · Accepted Answer

A, Z, and N describe the number of particles of given types (protons and neutrons) in the nucleus. The mass of the nucleus is not equal to the mass of the individual protons and neutrons, as some of the mass is converted to nuclear binding energy. Therefore, while A, Z, and N do not directly give the mass of the nucleus, they still provide useful information about its composition.

How Can a Nucleus Be Described by Particular Values of A