Question

a sample that has a half life of 45 years take ____ for the count rate to drop from 600 cpm to 150 cpm

Answer 1

90yrs

Step-by-step explanation:

Half life is the time taken for half of an original radioactive material to decay by half.

For the sample;

Half - life = 45yrs

Original amount = 600cpm

Start Number of atoms

0yrs 600cpm

First half life

45yrs 300cpm

Second half life

90yrs 150cpm