An atom of an element can change into an atom of another element if it is A
extremely stable and has a long life.
B
radioactive and its nucleus emits or traps particles.
С
an isotope and it contains more electrons than neutrons.
D
an ion and its atomic number is larger than its mass number.

i think the answer would be 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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