* They are all diatomic molecules. This means they are composed of two atoms of the same element bonded together.
* They are all gases at room temperature and pressure. This is due to the weak intermolecular forces between the molecules.
* They are all essential for life on Earth.
* O2 is needed for respiration by most living organisms.
* H2 is a component of water, which is essential for life.
* CO2 is used by plants for photosynthesis.
* N2 is the main component of the Earth's atmosphere and is used by bacteria to fix nitrogen for plant growth.
Let me know if you'd like more information about any of these molecules!
