Which of the following ions is a polyatomic ion? (points : 1) f ca2+ nh4+ cl

Among the choices, the polyatomic ion is only the third choice, NH4+ where it is composed of nitrogen one atom of nitrogen and 4 atoms of hydrogen. Choice 2 is a monoatomic atom being composed only of calcium. Then, the first and fourth choices are not ions because they are not charged.

I think to a degree we should have. In WWII I think entering the war was necessary after Pearl Harbor, but nowadays I think we need to focus on America first, and stop worrying about every little thing in other countries. America has a lot of problems it needs to fix, and pulling out of other countries affairs would be a good way to do so.