Select the correct answer.

The table lists the half-life for four different isotopes of sulfur. Equal amounts of each sample are stored in sealed jars. Which jar will contain the least amount of the isotope of sulfur after 10 seconds?

\begin{tabular}{|l|l|}
\hline
Isotope & \multicolumn{1}{|c|}{Half-life} \\
\hline
sulfur-30 & 1.18 seconds \\
\hline
sulfur-35 & 87.5 days \\
\hline
sulfur-37 & 5.05 minutes \\
\hline
sulfur-41 & 1.99 seconds \\
\hline
\end{tabular}

A. sulfur-30
B. sulfur-35
C. sulfur-37
D. sulfur-41



Answer :

To determine which jar will contain the least amount of the isotope of sulfur after 10 seconds, we need to understand how the amount of a radioactive substance decreases over time. The key concept here is the half-life, which is the time required for half of the original amount of the substance to decay. The formula for the remaining fraction of a substance after a given time is:

[tex]\[ \text{remaining\_fraction} = 0.5^{\left(\frac{\text{time\_elapsed}}{\text{half\_life}}\right)} \][/tex]

Let's calculate the remaining fraction for each isotope after 10 seconds:

1. Sulfur-30 (half-life = 1.18 seconds):
[tex]\[ \text{remaining\_fraction} = 0.5^{\left(\frac{10}{1.18}\right)} \approx 0.002811 \][/tex]

2. Sulfur-35 (half-life = 87.5 days = 87.5 \times 24 \times 3600 seconds):
[tex]\[ \text{remaining\_fraction} = 0.5^{\left(\frac{10}{87.5 \times 24 \times 3600}\right)} \approx 0.999999 \][/tex]

3. Sulfur-37 (half-life = 5.05 minutes = 5.05 \times 60 seconds):
[tex]\[ \text{remaining\_fraction} = 0.5^{\left(\frac{10}{5.05 \times 60}\right)} \approx 0.977384 \][/tex]

4. Sulfur-41 (half-life = 1.99 seconds):
[tex]\[ \text{remaining\_fraction} = 0.5^{\left(\frac{10}{1.99}\right)} \approx 0.030710 \][/tex]

The remaining fractions for the isotopes after 10 seconds are approximately:
- Sulfur-30: 0.002811
- Sulfur-35: 0.999999
- Sulfur-37: 0.977384
- Sulfur-41: 0.030710

By comparing these values, we can see that the smallest remaining fraction is for sulfur-30, which means it has decayed the most.

Therefore, the correct answer is:
A. sulfur-30