Answer:

The air in the atmosphere consists of nitrogen, oxygen, which is the life-sustaining substance for animals and humans, carbon dioxide, water vapour and small amounts of other elements (argon, neon, etc.). Higher in the atmosphere air also contains ozone, helium and hydrogen.
The answer would be 1,3,1,3
The answer is C due to the rain making contact with the iron it creates moisture which cause the iron to begin oxidizing which causes the iron to rust which is a chemical reaction then the blade which was once malleable because it was heat becomes harden and rust is created as I said before the physical aspect of the iron chances due to rust developing on it it's no longer has the luster it once had
A challenge they could face is that the plants are not used to the climate in the new area . (sorry if it’s wrong)