Question

A particular radioactive element has a half-life of 2.00 weeks. What percent of the original sample is left after 28.0 days?

Answer 1

After 28.0 days, 25% of the original sample is left.

Step-by-step explanation:

To calculate the percent of the original sample that remains after a certain time period, we can use the formula:

Percent remaining = (1/2)^(t/h) imes 100%

Where t is the time elapsed and h is the half-life of the radioactive element.

In this case, the half-life is 2.00 weeks and the time elapsed is 28.0 days. To convert 28.0 days to weeks, divide by 7:

28.0 days / 7 = 4.0 weeks

Plugging in these values into the formula:

Percent remaining = (1/2)^(4.0/2.00) imes 100%

Calculating this expression,

Percent remaining = (1/2)^(2) imes 100%

Percent remaining = (1/4) imes 100%

Percent remaining = 25%

Therefore, after 28.0 days, 25% of the original sample is left.