Which of the following is closest to the atomic mass of silicon (Si)?

• A. 28.09 u
• B. 12.01 u
• C. 24.31 u
• D. 32.07 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 the atomic mass listed on the periodic table for silicon (Si) is approximately 28 u, which reflects the average mass of its isotopes.
3. Compare the given options to the known atomic masses of common elements: 12.01 u corresponds to carbon, 24.31 u corresponds to magnesium, and 32.07 u corresponds to sulfur.
4. Identify that the value closest to silicon's atomic mass is 28.09 u, which matches the known average atomic mass of silicon.
5. Conclude that the correct choice is the value closest to 28.09 u, confirming the atomic mass of silicon.