Question
Tue September 17, 2013 By:
 

some metals appear dull?

Expert Reply
Vaibhav Chavan
Wed September 18, 2013
Metals when exposed to air for a long time develop a thin layer of oxide,carbonate or sulphide by the slow action of the various gases present in air.Due to oxidation, a new layer is formed giving the metals a dull appearance.
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