Question

how much of a radioactive kind of nitrogen will be left after 30 minutes if you start with 1,920 grams and the half - life is 10 minutes?

Explanation:

Step1: Calculate the number of half - lives.

The time elapsed is 30 minutes and the half - life is 10 minutes. So the number of half - lives $n=\frac{30}{10}=3$.

Step2: Use the radioactive decay formula.

The formula for radioactive decay is $A = A_0\times(\frac{1}{2})^n$, where $A_0$ is the initial amount and $n$ is the number of half - lives. Here, $A_0 = 1920$ grams and $n = 3$. So $A=1920\times(\frac{1}{2})^3$.

Step3: Calculate the remaining amount.

$A = 1920\times\frac{1}{8}=240$ grams.

Answer:

240