The average oxygen atom has a mass number of 16 and an atomic number of 8. This means that the number of neutrons in this oxygen atom is:

• A. 24.
• B. 8.
• C. 16.
• D. 4.
• E. 2.

Answer: (B)

Verified step by step guidance

1. Understand the concept of atomic number and mass number: The atomic number represents the number of protons in an atom, while the mass number is the sum of protons and neutrons.
2. Identify the atomic number of oxygen: According to the problem, the atomic number of oxygen is 8, which means it has 8 protons.
3. Identify the mass number of oxygen: The mass number given is 16, which is the total number of protons and neutrons in the atom.
4. Calculate the number of neutrons: Subtract the atomic number (number of protons) from the mass number to find the number of neutrons. Use the formula: \( \text{Number of neutrons} = \text{Mass number} - \text{Atomic number} \).
5. Perform the subtraction: Substitute the values into the formula: \( \text{Number of neutrons} = 16 - 8 \). This will give you the number of neutrons in the oxygen atom.