Argon, Ar Oxygen, O2 Water, H2O Nitrogen, N2
I am hesitating between 4 options to answer the following question, which option should I choose?
Question: Air is composed of many different substances. Which of the following components of air is a compound rather than an element?
Possibilities:
- Argon, Ar
- Oxygen, O2
- Water, H2O
- Nitrogen, N2

Water, H2O