1 條 科學 的問題 ( 英文 ) 急急急 !!!

chromium, zinc and sliver are the examples used to coat other metals.
There are several reasons, 2 common reasons are use to improve the appearance like sliver on fork and to protect the metals from rusting, like zinc on iron.

hope I can help you.

A little additional information: You might want to specify this process is called Galvanization. This process is mainly adopted to protect the coated metal in order to prevent corrosion (rusting).