Which of the following is closest to the atomic mass of helium?

• A. 4.00 u
• B. 6.94 u
• C. 1.01 u
• D. 2.00 u

Answer: (A)

Verified step by step guidance

1. Understand that the atomic mass of an element is the weighted average mass of all its naturally occurring isotopes, measured in atomic mass units (u).
2. Recall that helium is a noble gas with two protons and typically two neutrons in its most common isotope, which contributes to its atomic mass.
3. Recognize that the atomic mass is approximately the sum of the number of protons and neutrons in the nucleus of the most abundant isotope.
4. Compare the given options to the expected atomic mass based on helium's isotopes, knowing that helium's most common isotope has a mass number close to 4.
5. Select the value closest to 4.00 u, which corresponds to the atomic mass of helium.