Answer:
90yrs
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
You can find the answer on google for this
Plants use carbon dioxide, and put out oxygen, so it's like a cycle there. plants have roots to collect water from the soil around them. And they use the sun for energy.
