the half - life of a radioactive kind of protactinium is 27 days. how much will be left after 54 days, if…

Explanation:

Step1: Calculate number of half - lives

The half - life is 27 days and the time elapsed is 54 days. The number of half - lives $n=\frac{54}{27}=2$.

Step2: Use the half - life formula

The formula for the amount of a radioactive substance remaining 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, $A_0 = 488$ grams and $n = 2$. So $A=488\times(\frac{1}{2})^2$.

Step3: Calculate the remaining amount

$A = 488\times\frac{1}{4}=122$ grams.

Answer:

122