Answer:
12 years
Explanation:
We are given;
Half life of hydrogen-3 is 12 years
Initial mass of Hydrogen-3 is 20 grams
Final mass will be 10 g because we are told half of the sample will decay.
To find the time taken for the decay we need to know what half life is;
- Half life is the time taken for a radioactive isotope to decay to half its original amount.
Remaining mass = Original mass × 0.5^n
n = number of half lives
therefore;
10 g = 20 g × 0.5^n
0.5 = 0.5^n
n = log 0.5 ÷ log 0.5
= 1
But, 1 half life is 12 years
Therefore, the time taken is 12 years
