Answer: Two possible ways to show the structure of CH4 are its electron dot diagram or structural formula. CH4 or methane's molecular formula is given as CH4. The structural formula is a graphical representation of a chemical compound.
If a solution is saturated, that means it already posses the maximum number of solutes thus have been dissolved in it, and thus the concentration cannot be increased.
Here try this presentation, it should help :)
https://prezi.com/6ofdo3fadl9a/exothermic-and-endothermic-reactions-in-everyday-life/
The answer for the first question would be water. It is the substance that is a compound since it is made up of different elements. For the second item, i think the best answer is phosphorus and nitrogen. They are the limiting nutrients. For the last item, the correct answer is reservoirs.
