Mars.
Mars
Yes, the iron oxide in the rock actually gives the planet a reddish color. Mars is actually rusting.
Iron oxidation (transformation of iron in iron oxides)
planet x
The planet Earth or the earth (as soil) doesn't suffer from rusting.
Mercury
neptune
Neptune
Neptune
I couldn't find information about such a planet. If it appears in some television story, or book, it may be a fictional planet.
Neptune, the furthest planet from the sun.
earth