Which of the following values is closest to the atomic mass of a helium atom?

• A. 6 amu
• B. 4 amu
• C. 14 amu
• D. 10 amu

Answer: (B)

Verified step by step guidance

1. Understand that the atomic mass of an element is approximately the sum of the number of protons and neutrons in its nucleus, measured in atomic mass units (amu).
2. Recall that helium has an atomic number of 2, meaning it has 2 protons in its nucleus.
3. Recognize that the most common isotope of helium has 2 neutrons, so the total number of nucleons (protons + neutrons) is 2 + 2 = 4.
4. Therefore, the atomic mass of a helium atom is close to 4 amu, since electrons contribute negligibly to the mass.
5. Compare the given options and identify that 4 amu is the value closest to the atomic mass of helium.