Which element has its most common isotope containing 5 neutrons?

• A. Oxygen
• B. Boron
• C. Carbon
• D. Nitrogen

Answer: (B)

Verified step by step guidance

1. Recall that the number of neutrons in an isotope is given by the difference between the mass number (A) and the atomic number (Z) of the element: \(\text{Number of neutrons} = A - Z\).
2. Identify the atomic number (Z) of each element, which corresponds to the number of protons and is unique for each element: Oxygen (8), Boron (5), Carbon (6), Nitrogen (7).
3. For each element, consider its most common isotope, which usually has a mass number (A) close to the sum of protons and neutrons in the most abundant form.
4. Calculate the number of neutrons for the most common isotope of each element by subtracting the atomic number from the mass number: for example, for Boron, if the most common isotope has a mass number of 10, then neutrons = 10 - 5 = 5.
5. Compare the calculated number of neutrons for each element's most common isotope to find which one has exactly 5 neutrons.