Which of the following is closest to the atomic mass of calcium (Ca)?

• A. 24.31 u
• B. 40.08 u
• C. 12.01 u
• D. 55.85 u

Answer: (B)

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 calcium (Ca) is an element with atomic number 20, and its atomic mass is typically found on the periodic table.
3. Compare the given options to the known atomic masses of common elements: 24.31 u corresponds approximately to magnesium, 12.01 u to carbon, 55.85 u to iron, and 40.08 u to calcium.
4. Identify that the atomic mass closest to calcium's known atomic mass is 40.08 u, based on the periodic table values.
5. Conclude that the correct choice is the value closest to calcium's atomic mass, which is 40.08 u.