A 30 kg child climbs 15 meters up a tree. When he stops to have a look around, what is the child's gravitational potential energy?

Which of these best describes an ionic bond?

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?

Which statement about hf is true? it is zero for any compound in its standard state. it is positive when the bonds of the product store more energy than those of the reactants. it is negative when a compound forms from elements in their standard states. it is zero for any element that is in the liquid state.