Which of the following isotopes has 8 neutrons in its nucleus?

• A. Fluorine-19 (19F)
• B. Nitrogen-15 (15N)
• C. Carbon-14 (14C)
• D. Oxygen-16 (16O)

Answer: (D)

Verified step by step guidance

1. Recall that the number of neutrons in an isotope is found by subtracting the atomic number (number of protons) from the mass number (total number of protons and neutrons). The formula is: \(\text{Number of neutrons} = \text{Mass number} - \text{Atomic number}\).
2. Identify the atomic number (number of protons) for each element: Fluorine (F) has atomic number 9, Nitrogen (N) has atomic number 7, Carbon (C) has atomic number 6, and Oxygen (O) has atomic number 8.
3. Calculate the number of neutrons for each isotope by subtracting the atomic number from the mass number: For example, for Oxygen-16, neutrons = 16 - 8.
4. Compare the calculated number of neutrons for each isotope to find which one has exactly 8 neutrons.
5. Select the isotope whose neutron count matches 8, confirming that Oxygen-16 (16O) has 8 neutrons in its nucleus.