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.
Explanation:
an acid will give away a proton and become a conjugate base.
A base will accept a proton and become a conjugate acid.
it is c. ionic compound just because it says ionic. can't be a crystal since there's no links to an ionic bond connected to crystals (and if it were it'd depend on the elements and the thingy majig itself right) and a covalent bond is an entirely different bond which isn't related to ionic. hope this helped, and i hope you have a good day too! :D
1: it is +2
2: it is +6
(Make this brainliest answer please)
The answer should be D, cells can only create an identical copy of the original cell.
