Which element has an isotope with 16 neutrons and a mass number of 30?

• A. Sulfur (S)
• B. Magnesium (Mg)
• C. Silicon (Si)
• D. Phosphorus (P)

Answer: (D)

Verified step by step guidance

1. Recall that the mass number (A) of an isotope is the sum of the number of protons (Z) and neutrons (N): \(A = Z + N\).
2. Given the mass number \(A = 30\) and the number of neutrons \(N = 16\), use the formula to find the number of protons: \(Z = A - N = 30 - 16\).
3. Calculate \(Z\) to find the atomic number, which identifies the element on the periodic table.
4. Look up the element with atomic number \(Z\) on the periodic table to determine which element has an isotope with 16 neutrons and mass number 30.
5. Confirm that the element with atomic number \(Z\) matches the correct answer, Phosphorus (P), which has atomic number 15.