Question
Which pure substance can be classified as an element?
H2
NO3
NaCl
H2SO4
H2
NO3
NaCl
H2SO4
Answers
GPT-4o mini
Among the options provided, the pure substance that can be classified as an element is **H₂** (molecular hydrogen). An element is a substance that cannot be broken down into simpler substances and consists of only one type of atom. H₂ is a diatomic molecule composed solely of hydrogen atoms.
The other options are:
- **NO₃**: This is a polyatomic ion (nitrate), not a pure substance in the context of an element.
- **NaCl**: This is a compound (sodium chloride) made up of sodium and chlorine, which are both elements.
- **H₂SO₄**: This is sulfuric acid, which is a compound made up of hydrogen, sulfur, and oxygen.
Therefore, the correct answer is **H₂**.
The other options are:
- **NO₃**: This is a polyatomic ion (nitrate), not a pure substance in the context of an element.
- **NaCl**: This is a compound (sodium chloride) made up of sodium and chlorine, which are both elements.
- **H₂SO₄**: This is sulfuric acid, which is a compound made up of hydrogen, sulfur, and oxygen.
Therefore, the correct answer is **H₂**.