Achange in heat whether endothermic or exothermic is always a clear indication of a chemical change true or false?

True

Explanation:

During a chemical reaction energy is used, whether to break bonds in reactants or make new bonds forming products. When bonds are broken (reactants) energy is absorbed, this is termed an endothermic reaction. When bonds form (products), energy is released, this is an exothermic reaction.

the density(ratio between mass and volume as m/v) decreases from top to bottom in periodic table group as the size increases and nuclear charge decreases. but in periods density increases from left to right as atom size decreases and nuclear charge increases.

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.