I need help ! I don’t understand the concept of this question

Determine the mass of fuel required for the expected energy consumption in the united states for the next ten years. energy use per person per year in the united states = 3.5 x 1011joules base calculations on current population of 310,000,000.

If you have 5.25 grams of methane (ch4), how many grams of co2 will you produce ?

Chen drew a diagram to compare the ways in which different organisms obtain nitrogen. which label belongs to the area marked z?