An isotope has a half-life of 3.0 days. What fraction of the sample is left after 15
days?

are there answer choices to this question? this seems like a question where you have options to choose from.

as we know our atmosphere or air have different levels. every level has other gasses, and every gas has another permeability. when the light comes from lower permeability to higher permeability, it changes its direction. so that means that when the light comes from the moon to the earth, it changes it's direction many more times. it basically means that the shape of the light part of the moon is changed on the earth.

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