Zircon crystals form from volcanic rock. The age of zircon crystals can be precisely measured. What ...

Answer to q. 1

Zircon consists mainly of ordered arrays of zirconium silicate molecules (ZrSiO4). Some of the molecules in a newly formed zircon crystal have uranium atoms substituted for zirconium atoms. Uranium decays into lead. Therefore, the ratio of uranium atoms to lead atoms can be used to calculate the age of the crystal.

Answer to q. 2

While an organism lives, it exchanges carbon with the environment and the ratio of normal carbon (carbon-12) to radioactive carbon (carbon-14) remains stable. At death, the exchange stops and the amount of carbon-14 decreases as it goes through radioactive decay. Since carbon-14 has a known half-life (5370 years), the decrease can be measured and related to time since death. (e.g., an organism with one-fourth the normal amount of carbon-14 died about 10000-11000 years ago--two half-lives)

This helps so much, thank you for responding so quickly...

No worries, I was online and bored