The same water molecules that are on our earth right now is the same water molecules that have been here for millions of years. Water does not leave our atmosphere. True
False

it's true

Explanation:

the water present on earth today is the same water that is present on the earth from millions of days, cuz neither it left our atmosphere and didn't get in our atmosphere.

chemical changes occur when a substance combines with another to form a new substance, called chemical synthesis or, alternatively, chemical decomposition into two or more different substances. these processes are called chemical reactions and, in general, are not reversible except by further chemical reactions. some reactions produce heat and are called exothermic reactions and others may require heat to enable the reaction to occur, which are called endothermic reactions. understanding chemical changes is a major part of the science of chemistry.