Question

give one example in which corrosion is an advantage rather than a disadvantage

Answer 1

1. One example is the formation of aluminium oxide over the Aluminium ,which further protects the deterioration of Aluminium and act as barrier for air and moisture.

Hope it helps you!

Answer 2

In case of magnesium (Mg), it reacts with air to produce magnesium oxide(MgO).
It helps to protect the magnesium strip/ribbon/wire from decomposing further (as magnesium oxide doesn't let the element to come in contact with more air and stops decomposition.)