A gas. This is because none polar solvents contain binds between atoms with similar electronegativities, some examples are carbon and hydrogen
A population is essentially just a collection of all living things in one category. People are one population, insects are another, etc. Communities are "more organized" populations. Soccer players hang out with soccer players, spiders hang out with spiders. We split into "our people" within our population.
I know that may be a little confusing, but if you have anymore questions feel free to ask. I hope I was able to help. Best of luck!
Endocrine system is the answer
Its often referred to as the colon