Question

Potassium-40 decays to argon-40 with a half-life of 1.27 x 109 yr. The age of a mineral sample that has a mass ratio of 40Ar to 40K of 0.330 is yr. Answer: 5.23 x 108 4) If we start with 1.000 g of strontium-90,0.805 g will remain after 9.00 yr. This means that the half- life of strontium-90 is yr. Answer: 28.8 5) A freshly prepared sample of curium-243 undergoes 3312 disintegrations per second. After 8.00 yr the activity of the sample declines to 2591 disintegrations per second. The half-life of curium-243 is years.

Answer 1

Radioactive decay is used to determine the age of materials by comparing the ratio of parent isotopes to daughter products, with knowledge of the specific isotope's half-life.

Step-by-step explanation:

The concept you are asking about is related to the radioactive decay of isotopes and the use of half-life information to date materials such as rocks or carbon-containing objects. The half-life of an isotope is the time it takes for half of the radioactive nuclei in a sample to decay. This can be used to date materials by comparing the ratio of the parent isotope to the daughter isotope that it decays into, as seen in potassium-argon dating. For example, if we know the half-life of a specific isotope, we can determine the age of a rock by measuring the ratio of the remaining isotope to the amount that has decayed into its daughter product.

For instance, with potassium-40 decaying into argon-40, if a rock sample has a ratio of 0.330 of 40Ar to 40K, by using the half-life of 1.25 billion years for 40K, one can calculate the age of the sample. Similarly, the decay of strontium-90 or curium-243 can inform us about the history and timing of processes such as nuclear waste production or the use of radioactive tracers in medicine.