Which allowed scientists to determine that earth was at leat 4.3 billion years old?

Question

magnetic field surrounding zircon
chemical reactivity of zicron ions
the radioactive decay of uranium to lead
the electrical conductivity of uranium ions

Answer 1

The radioactive decay of uranium to lead allowed scientists to determine that Earth was at least 4.3 billion years old. This is because uranium undergoes radioactive decay over time, and by measuring the ratio of uranium to lead in rocks or minerals such as zircon, scientists can calculate the age of the sample.