All of the different organisms interacting in a pond make up 1.) a community
2.)the water cycle
3.) a population
4.) the habitat

they would make up a population

Explanation:

all the inhabitants of a particular town, area, or country.

the population of frogs are very difficult to catch

idk i’m struggling too

the density(ratio between mass and volume as m/v) decreases from top to bottom in periodic table group as the size increases and nuclear charge decreases. but in periods density increases from left to right as atom size decreases and nuclear charge increases.