Final answer:
Isotope B of sodium would have the same number of protons (11) and electrons (11) as isotope A to remain a sodium atom, but the number of neutrons could be different, resulting in a different mass number.
Step-by-step explanation:
The question revolves around the concept of isotopes, which are atoms of the same element that have the same number of protons but different numbers of neutrons. Isotope A of sodium has 11 protons, 11 electrons, and 12 neutrons, giving it a mass number (atomic mass) of 23 (since mass number = protons + neutrons).
For isotope B of sodium, the number of protons (11) and electrons (11) must remain the same because the number of protons defines the element, and a neutral atom will always have equal numbers of protons and electrons. However, the number of neutrons can be different. If we assume isotope B has 13 neutrons, for example, the mass number would be 24 (11 protons + 13 neutrons).
Remember, the atomic structure of isotope B could vary, as the number of neutrons in isotopes of an element can change. Therefore, isotope B of sodium could have more or less than 12 neutrons, but it must have 11 protons and 11 electrons to still be a sodium atom.