Question

The radioisotope C-11 has a half-life of 20 mins. How many half-lives have elapsed after 2 hours?

Answer 1

`6`

Step-by-step explanation:

Here, we want to get the number of half-lives that would have elapsed

Firstly, we need to get the number of 20 minutes in 2 hours

In two hours, since there are 60 minutes in an hour, there would be a total of 120 minutes

Now, the number of 20 minutes in 120 minutes would be:

`(120)/(20)\text{ = 6 half-lives}`