Pure water is solution or compound or element or mixture

compound

Explanation:

water is a 'mixture' of 2 elements, hydrogen and oxygen, therefore it is a compound.

Hence H2O, 2 hydrogen atoms and 1 oxygen atom.

a rain shadow is a dry region of land on the side that is protected against the prevailing winds of a mountain range. the prevailing winds are the winds that occur most of the time in a particular place of the earth

prevailing winds carry air toward the mountain range. as the air rises up over a mountain range, the air cools, water vapor condenses, and clouds form. on this side of the mountains, called the windward side, precipitation falls in the form of  rain  or snow. this dry air produces a  rain shadow.