Over time, carbon-14 decays in predictable ways. And with the help of radiocarbon dating, researchers can use that decay as a kind of clock that allows them to peer into the past and determine absolute dates for everything from wood to food, pollen, poop, and even dead animals and humans.

Can water be broken down by a chemical change?

Salt and other compounds can only be decomposed into their elements by a chemical process. A chemical change is a change that produces matter with a different composition. Water is still a compound, but one which cannot be broken down into hydrogen and oxygen by heating.