Neutral Atom Particle Composition

Steps:

• Atomic number Z gives the number of protons in the nucleus.
• Mass number R gives the total nucleons, so neutrons = R - Z.
• In a neutral atom, electrons equal protons, so electrons = Z.
• Total particles = protons + neutrons + electrons = Z + (R - Z) + Z = Z + R.

Why C is correct:

• Z + R equals mass number plus atomic number, which is protons + neutrons + electrons by definition of neutral atom structure.

Why the others are wrong:

• A. Z counts only protons (or electrons), excluding neutrons and the other set of electrons.
• B. R counts only protons + neutrons, excluding electrons.
• D. Z² + R has no physical basis in atomic structure.

Final answer: C