Question

The table below shows the initial and final masses of a radioactive material whose half-life is 15 years.

Answer 1

Answer:

A

Explanation:

1 half-life = .4 kg = 15 years

2 half-life = .2 kg = 30 years

3 half-life = .1 kg = 45 years

4 half-life = .05 kg = 60 years

Answer 2

Answer:

A

Explanation:

Initial mass is 8. The half-life is 15 years.

1st half life=.8/2=.4

2nd half life=.4/2=.2

3rd half life=.2/2=.1

4th half life=.1/2=.05

For each half life that it took it to go from .8 to 0.05, you add 15 years since that is the half life of the substance. 4*15=60.

So, the answer is A. The material decayed from 0.8 kilograms to 0.05 kilogram in 60 years.