Question

1. students are provided a sample of an element with a table describing the composition.

element sample’s properties

isotope	atomic mass (amu)	percent abundance
b	28.976495	4.67
c	29.973770	3.10

what is the average atomic mass of the substance? use significant figures.

Explanation:

Step1: Convert percentages to decimals

For Isotope A: $92.23\% = 0.9223$
For Isotope B: $4.67\% = 0.0467$
For Isotope C: $3.10\% = 0.0310$

Step2: Calculate contribution of each isotope

Isotope A: $27.976927 \times 0.9223$
Isotope B: $28.976495 \times 0.0467$
Isotope C: $29.973770 \times 0.0310$

Step3: Sum the contributions

First, calculate each product:
Isotope A: $27.976927 \times 0.9223 \approx 25.803$
Isotope B: $28.976495 \times 0.0467 \approx 1.353$
Isotope C: $29.973770 \times 0.0310 \approx 0.929$

Then sum: $25.803 + 1.353 + 0.929 = 28.085$

Answer:

The average atomic mass is approximately $\boldsymbol{28.09}$ amu (rounded to four significant figures, considering the percent abundances and atomic masses).