Final answer:
A neutral atom of calcium has 20 protons and 20 electrons, so the correct answer is A) Protons: 20, Electrons: 20.
Step-by-step explanation:
In a neutral atom of calcium, the number of protons and electrons is the same, as atoms are electrically neutral. Calcium has an atomic number of 20, which means it has 20 protons. Since the atom is neutral, it must also have 20 electrons to balance the positive charge of the protons.
Thus, for a neutral calcium atom, the correct answer is A) Protons: 20, Electrons: 20. When a calcium atom forms a cation, it loses two electrons, resulting in a Ca²⁺ ion with 20 protons, 18 electrons, and a 2+ charge. However, as the question specifies a neutral atom, we focus on the uncharged state with an equal number of protons and electrons.