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: The atomic number of oxygen is given as 8, which means there are 8 protons in the oxygen atom.
3. Identify the mass number of oxygen: The mass number of oxygen is given as 16, which is the total number of protons and neutrons.
4. Calculate the number of neutrons: To find the number of neutrons, subtract the atomic number from the mass number. Use the formula: $\mathrm{mass} \mathrm{number} - \mathrm{atomic} \mathrm{number}$
5. Perform the subtraction: Substitute the values into the formula: $16-8$ to find the number of neutrons.