I'm confused about this question. 3. What form is energy in when it enters a food chain and when it leaves a food chain?
That is how it's written on the paper...

the speed increase from w to x due to increased gravity force

the speed decreases from x to y due to decrease in gravity

when atoms of different types of elements join together, they make molecules called compounds. water consists of compound molecules made up of 2 hydrogen atoms and 1 oxygen atom. this is why it's called h2o. water will always have 2 times the number of hydrogen atoms as oxygen atoms.