Which of the following elements is the most chemically reactive? A. Iron
B. Fluorine
C. Boron
D. Argon

B) Fluorine

Explanation:

The most reactive element is fluorine, the first element in the halogen group. The most reactive metal is francium, the last alkali metal (and most expensive element).

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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causes

fossil fuels burn

cities become more industrialized

human population grows worldwide