If atomic nuclei A has 94 protons and 146 neutrons, and nuclei B has 94 protons and 150 neutrons, what can we determine about A and B?

In this scenario, both atomic nuclei A and B have the same number of protons, which is 94. The number of protons in the nucleus is the defining characteristic of an element; hence, both nuclei belong to the same element, which is plutonium (Pu).

The difference in the number of neutrons, with A having 146 and B having 150, leads to the understanding of isotopes. Isotopes are defined as variants of the same element that contain the same number of protons but different numbers of neutrons. Therefore, because A and B have different numbers of neutrons while having the same number of protons, they are indeed different isotopes of plutonium.

This understanding confirms that the correct conclusion is that they are different isotopes of the same element.