Use the data in the table to calculate the atomic mass of silicon.

Exact Mass and Abundance of 3 Isotopes of Silicon

Isotope	Isotopic Mass	Abundance
28Si	27.97693 amu	92.23%
29Si	28.97649 amu	4.67%
30Si	29.97376 amu	3.10%

• A. 28.976 amu
• B. 28.97649 amu
• C. 28.09 amu
• D. 29 amu

Answer: (C)

Verified step by step guidance

1. Identify the isotopes of silicon and their respective isotopic masses and abundances from the table: 28Si with 27.97693 amu and 92.23% abundance, 29Si with 28.97649 amu and 4.67% abundance, and 30Si with 29.97376 amu and 3.10% abundance.
2. Convert the percentage abundances into decimal form by dividing each percentage by 100. For example, 92.23% becomes 0.9223.
3. Calculate the contribution of each isotope to the atomic mass of silicon by multiplying the isotopic mass of each isotope by its decimal abundance. For example, for 28Si, multiply 27.97693 amu by 0.9223.
4. Sum the contributions of all isotopes to find the average atomic mass of silicon. This involves adding the results from the previous step for each isotope.
5. The sum obtained from the previous step represents the atomic mass of silicon, which is a weighted average based on the natural abundance of each isotope.