Which are pure elements?

Question

H2, H20, HE, Na,Nacl,H2SO4, or U

Answer 1

Pure elements are those indicated by only one alphabetic symbol. For example, CuSO4 is a compound, Cu is an element, as are S and O (or O2).

Answer 2

I think you refer to which ones from the list are either compounds (i.e. molecules) or atoms. I think by pure you mean single atoms.

Atoms (single) - He (helium) Na (sodium) U (uramium)
Diatomic molecules (made from same element but we have two atoms instead of one) - H2 (hydroden molecule)
Compounds (molecules made up from different elements) - H2O (water), NaCl (sodium chloride - salt) and H2SO4 (sulphuric acid)

Answer 3

the pure elements are H2, which is hydrogen, HE, helium, Na, sodium, and u, Uranium. NaCl is sodium chloride, common table salt, H2O is dihydrogen monoxide, or water, and the last one, idk, i just know that that is some sort of organic molecule

Answer 4

HE(He),Na,U.

Pure element:
Chemical element consisting of only one stable isotope; e.g. fluorine, aluminium, gold.