O2 isn't necessary for rusting, but some source of oxygen is required. Rust is just another name for iron oxide, and without oxygen there can't be oxide.
Hope this helps,
Davinia.
Answer:
Gases can be compressed easily because there is a large amount of space between the individual molecules, which are very active and move around at high speed.
Explanation:
When gas is compressed, the particles are forced much closer together, allowing a huge amount of particles to fit in a small space.
Most of the light passes through glass but none of the light passes through metal.
A potassium atom has a higher proton number meaning that it has more protons and electrons. Due to the Octet Rule, the more electrons an atom has the more shells it has and so will be bigger in size.
Hope this was helpful x