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Gases are one of the four fundamental states of matter alongside solids, liquids and plasma. They are made up of atoms and molecules like other matter but don’t have a fixed shape or volume. Gases take the shape of whatever container they are confined to and even expand to fill that container.
Though gases are often thought to be invisible, many actually have distinctive colours. For example, nitrogen dioxide is a browny-orange sort of colour, while chlorine is a greenish yellow. Even common gases like oxygen and water vapour absorb light, just not at ultraviolet and infrared wavelengths that we can see.
“There’s a sweet spot between the absorption spectra of oxygen and water where not much light gets absorbed. Lo and behold, that’s exactly the range of light that we’ve evolved to see!” chemist and science communicator Professor Mark Lorch, from the University of Hull, previously told Science Focus.
“So it’s not that gases are invisible, as such, it’s just that we can’t see atmospheric gases as they don’t have a colour in the visible range.”
What is the structure of gas?
The particles in a gas are able to move freely and separate from each other without a fixed arrangement. This makes the structure of a gas very...