# are there any resource for the Abundance ratio of nuclear isotopes in early earth

The abundance ratio of a nuclide is the ratio of the number of atoms of one isotope to the number of atoms of another isotope of the same chemical element. It may also refer to the ratio of one isotope to the total number of atoms in a single-element sample. this is an example of The abundance ratio: $$U_{92}^{235}=0.720$$%. $$U_{92}^{238}=99.275$$%.

1. how we can measure The abundance ratio of a nuclide?

2. are there any resource for the Abundance ratio of nuclear isotopes in early earth!?

3. How old is planet Earth !?(Accurate)

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Re question 1: you'd typically measure the abundance ratio by putting a sample of your element in a mass spectrometer and counting how many atoms of the different masses you get. This is exactly how carbon dating works: it counts the C$^{12}$ and C$^{14}$ atoms and the ratio tells you how much C$^{14}$ has decayed.