Question

How much of a 1500. mg sample of potassium-42 is left after 48 hours if its half-life is 12.4hours?

Answer 1

Given data

*The initial quantity of potassium-42 is 1500 mg

*The given time is t = 48 hours

*The half-life of Potassium - 42 is T = 12.4 hours

The expression for the radioactive decay is given as

`A(t)=A_0((1)/(2))^{\frac{t}{T_{}_{}_{}}}`

Substitute the values in the above expression as

`\begin{gathered} A(48)=1500((1)/(2))^{(48)/(12.4)} \\ =102.59\text{ mg} \end{gathered}`