The answer is C. there are two potassium ions for each ion of sulfur
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.
most metals conduct electricity and are very dull to the look. most metals are toxic if eaten and are hard.
aluminum is a type of metal they is softer than the opther and conducts eletricty like a boss.
nickel on the opther hand is also a metal but does not conduct a lot of electricy.
metals can be bent and others can break,
I believe it’s Non polar molecule