Chapter 16, Problem 3TC

Rank the following isotopes in order of their radioactivity starting with the most radioactive isotope to least radioactive isotope:

$\left(a\right)$ Nickel-59, half-life $75,000\text{years}$

$\left(b\right)$ Uranium-238, half-life $4.5\text{billion}\text{years}$

$\left(c\right)$ Actinium-225, half-life $10\text{days}$

To determine

Ranking of the isotopes from most radioactive isotope to least isotope.

Answer to Problem 3TC

The ranking of the isotopes Uranium-238, Nickel-59 and Actinium-225 from most radioactive to least isotope is (b), (a), (c).

Explanation of Solution

The duration in which the initial amount of any radioactive material reduces to its half is called the half-life of radioactive material. The higher the half-life of radioactive material more is the time to reduce it to half of the initial amount of radioactive material. The radioactive material which having the half-life is greatest, then the radioactive effect of this material will also be greatest.

The half-life of the Uranium-238 is greatest and half-life of the Actinium-225 is least, so the Uranium-238 is most radioactive isotope and Actinium-225 is the least radioactive isotope. The radioactive isotope Nickel-59 is less radioactive than Uranium-238 but more radioactive than Actinium-225.

Conclusion:

Therefore, the ranking of the isotopes Uranium-238, Nickel-59 and Actinium-225 from most radioactive to least isotope is (b), (a), (c).