select the correct answer. if two half - lives have passed since a scientist collected a 1.00 - gram sample…

select the correct answer. if two half - lives have passed since a scientist collected a 1.00 - gram sample of u - 235, how much u - 235 is left now? a. 0.001 g b. 0.100 g c. 0.250 g d. 0.450 g e. 3.00 g

select the correct answer. if two half - lives have passed since a scientist collected a 1.00 - gram sample of u - 235, how much u - 235 is left now? a. 0.001 g b. 0.100 g c. 0.250 g d. 0.450 g e. 3.00 g

Answer

Explanation:

Step1: Recall half - life formula

The formula for radioactive decay is $N = N_0\times\left(\frac{1}{2}\right)^n$, where $N_0$ is the initial amount, $n$ is the number of half - lives, and $N$ is the remaining amount.

Step2: Identify values

Here, $N_0=1.00$ g and $n = 2$.

Step3: Calculate remaining amount

$N=1.00\times\left(\frac{1}{2}\right)^2=1.00\times\frac{1}{4}=0.250$ g

Answer:

C. 0.250 g