What is the half-life of an isotope that decays to 25% of its original activity in 70.8 hours?

b

explanation:

bc its just b

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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one "light year" is the distance that light travels, through vacuum, in one julian year.   that's 365.25 days, of 24 hours each.