How is the amount of matter available on earth very different from the amount of energy available

 I would say that the amount of available matter on earth is constant (since matter can neither be created nor destroyed), but the amount of available energy continually decreases. This is because the Second Law of Thermodynamics says that whenever energy is changed from one form to another, some is always lost as heat and becomes unavailable.

Hope this helped!

they absorb it i think

not sure

you

i believe it is "they are not used up by reactions" as the answer to your question, text me back if this is correct because i just learned this.