Respuesta :
If a rock contains 25% parent isotopes and 75% daughter isotopes, then two half-lives have passed.This is because, after one half-life, half of the parent isotopes will have decayed into daughter isotopes. So, after two half-lives, 75% of the parent isotopes will have decayed.
The half-life of a radioactive isotope is the time it takes for half of the atoms to decay. The half-life of an isotope is constant regardless of how much of the isotope is present.
There are a few different ways to calculate the half-life of rocks using isotopes.
One way is to use the decay constant of the isotope. The decay constant is the probability of an atom decaying per unit time. The half-life is then calculated by taking the natural logarithm of 2 and dividing it by the decay constant.
Another way to calculate the half-life of rocks using isotopes is to use the half-life formula.
The half-life formula is:
t ½ = ln(2) / λ
Where t1⁄2 is the half-life and λ is the decay constant ( λ = 0.693 )
t ½= ln(2) / 0.693
t ½= 0.693 / 0.693
t ½ = 11 t ½ from 100% to 50%
2 t ½ from 50% to 25%
The rock has 25% of Original Parent rock and 75% of Daughter Material, which means it has passed 2 half-life cycles.
Learn more about half-life at : brainly.com/question/24710827
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