Question

which pure substance can be classified as an element?
o h₂
o no₃
o nacl
o h₂so₄

Explanation:

An element is a pure substance made of only one type of atom. $H_2$ is a molecule of hydrogen, which is an element. $NO_3$ is a poly - atomic ion, $NaCl$ is a compound made of sodium and chlorine, and $H_2SO_4$ is a compound made of hydrogen, sulfur and oxygen.

Answer:

$H_2$