Question

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

Explanation:

Step1: Recall the definition of an element

An element is a pure substance made up of only one type of atom.

Step2: Analyze each option

• $H_2$: It is composed of only hydrogen atoms and is an element (in the form of a di - atomic molecule).
• $NO_3$: It is a poly - atomic ion, composed of nitrogen and oxygen atoms, not an element.
• $NaCl$: It is a compound made up of sodium and chlorine atoms.
• $H_2SO_4$: It is a compound composed of hydrogen, sulfur and oxygen atoms.

Answer:

$H_2$