Question

which pure substance can be classified as an element?

\\(\text{no}_3\\)

\\(\text{h}_2\text{so}_4\\)

\\(\text{h}_2\\)

\\(\text{nacl}\\)

Explanation:

Define elements and compounds

An element is a pure substance consisting of only one type of atom. A compound is a pure substance composed of two or more different chemical elements chemically bonded together.

Analyze the given options

• \(\text{NO}_3\) contains nitrogen (\(\text{N}\)) and oxygen (\(\text{O}\)), which are two different elements. Thus, it is a compound (or polyatomic ion).
• \(\text{H}_2\text{SO}_4\) contains hydrogen (\(\text{H}\)), sulfur (\(\text{S}\)), and oxygen (\(\text{O}\)), which are three different elements. Thus, it is a compound.
• \(\text{H}_2\) contains only hydrogen (\(\text{H}\)) atoms. Since it consists of only one type of atom, it is classified as an element (specifically, a diatomic element).
• \(\text{NaCl}\) contains sodium (\(\text{Na}\)) and chlorine (\(\text{Cl}\)), which are two different elements. Thus, it is a compound.

Identify the correct choice

Based on the analysis, \(\text{H}_2\) is the only pure substance listed that consists of a single type of atom and can be classified as an element.

Answer:

• \(\text{NO}_3\)
• \(\text{H}_2\text{SO}_4\)
• \(\text{H}_2\) (Correct answer)
• \(\text{NaCl}\)