Which of the following correctly describes how to calculate the number of neutrons (n) in an atom?

• A. Add the atomic number (Z) to the mass number (A): n = A + Z
• B. Divide the mass number (A) by the atomic number (Z): n = A / Z
• C. Subtract the atomic number (Z) from the mass number (A): n = A - Z
• D. Multiply the atomic number (Z) by the mass number (A): n = A imes Z

Answer: (C)

Verified step by step guidance

1. Understand the definitions: The atomic number (Z) represents the number of protons in an atom, and the mass number (A) represents the total number of protons and neutrons combined.
2. Recall that the number of neutrons (n) can be found by subtracting the number of protons from the total nucleons, since neutrons and protons together make up the mass number.
3. Write the relationship as an equation: \(n = A - Z\), where \(n\) is the number of neutrons, \(A\) is the mass number, and \(Z\) is the atomic number.
4. Evaluate why the other options are incorrect: adding \(A\) and \(Z\) would double count protons, dividing \(A\) by \(Z\) does not represent neutron count, and multiplying \(A\) and \(Z\) is unrelated to neutron calculation.
5. Conclude that the correct method to calculate the number of neutrons is to subtract the atomic number from the mass number, using \(n = A - Z\).