To determine the mass contribution of [tex]\(Br-79\)[/tex], we can use the information given about its relative atomic mass and its natural abundance. Here's the step-by-step solution:
1. Identify the relative atomic mass of [tex]\(Br-79\)[/tex]:
The relative atomic mass of [tex]\(Br-79\)[/tex] is [tex]\(79.918\)[/tex] amu.
2. Identify the natural (fractional) abundance of [tex]\(Br-79\)[/tex]:
The natural abundance of [tex]\(Br-79\)[/tex] is given as [tex]\(50.69\%\)[/tex]. To use this value in calculations, we need to convert it into a fraction by dividing by 100.
[tex]\[
\text{Fractional abundance of } Br-79 = \frac{50.69}{100} = 0.5069
\][/tex]
3. Calculate the mass contribution of [tex]\(Br-79\)[/tex]:
The mass contribution of an isotope can be calculated by multiplying the relative atomic mass by its fractional abundance.
[tex]\[
\text{Mass contribution of } Br-79 = \text{Relative atomic mass of } Br-79 \times \text{Fractional abundance of } Br-79
\][/tex]
[tex]\[
\text{Mass contribution of } Br-79 = 79.918 \times 0.5069
\][/tex]
4. Determine the numerical result:
Performing the multiplication:
[tex]\[
\text{Mass contribution of } Br-79 \approx 79.918 \times 0.5069 \approx 40.51 \text{ amu}
\][/tex]
Therefore, the mass contribution of [tex]\(Br-79\)[/tex] is approximately [tex]\(40.51\)[/tex] amu.
Given the options:
- [tex]\(40.51 \text{ amu}\)[/tex] (Correct Answer)
- [tex]\(39.90 \text{ amu}\)[/tex]
- [tex]\(39.41 \text{ amu}\)[/tex]
- [tex]\(41.02 \text{ amu}\)[/tex]
The correct answer is [tex]\(40.51 \text{ amu}\)[/tex].
