Question

how can we prevent the rusting of iron

Answer 1

by applying grease, paint electroplating.

Answer 2

Hey friend here is your answer

.Special "weathering steel" alloys such as Cor-Ten rust at a much slower rate than normal, because the rust adheres to the surface of the metal in a protective layer.
.Galvanization.
.rust can also prevent by controlling the moisture in air.

hope it help you ^_^