A. 1.5 g
Explanation:
The half-life is the time taken for a radioactive sample to decay to half of its initial composition.
At the half-time, an original sample would have decayed into half
Some materials have very fast half-life in the order of a few seconds and minutes. Some takes years.
The faster the half-life of a material, the more unstable it is.
Now to the problem,
Half- life of sample = 700 million years
Original mass of sample = 12g
Problem;
Mass of sample left after 2100 years = ?
Solving:
Time line using half life:
Start:
0yrs 700yrs 1400yrs 2100yrs
Sample:
mass 12g decays 6g decays 3g decays 1.5g
At the end of 2100yrs, we are going to have 1.5g sample of the uranium left.
learn more:
Radiometric dating brainly.com/question/7022607
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