The radioisotope, tritium 13(H) has a half-life of 12.3 years. If the initial amount of tritium is 32 mg, how many milligrams of it would remain after 49.2 years:
1 mg
2 mg
4 mg
8 mg
To determine how much tritium remains after 49.2 years, we need to use the concept of radioactive decay and half-life. The half-life of tritium \((^3_1H)\) is the time required for half of the radioactive nuclei to decay.
The formula to calculate the remaining amount of a radioisotope after a certain period is given by:
N = N_0 \left(\frac{1}{2}\right)^{\frac{t}{t_{1/2}}}
where:
Substituting the given values into the formula, we have:
N = 32 \left(\frac{1}{2}\right)^{\frac{49.2}{12.3}}
Calculate the exponent:
\frac{49.2}{12.3} = 4
Thus, the formula becomes:
N = 32 \left(\frac{1}{2}\right)^{4}
Calculate the power of the half:
N = 32 \times \frac{1}{16}
Therefore, N = 2 \, \text{mg}.
After 49.2 years, 2 mg of the initial 32 mg of tritium will remain.