Asubstance can be classified by it's physical properties, which are properties

An object becomes electrically charged when: electrons are created in it electrons from it are destroyed electrons are transferred to it protons from it are destroyed protons are created in it

About 3% of the water on earth is freshest. only about 40% of that freshwater is available for human use. why is so much freshwater unavailable for human use?

The fact that the total amount of energy in a system remains constant is a(n)