Question

metal are said to be sny.then why do metals generally appear to be dull?how can their too brightness be restored

Answer 1

Metals appear dull due to the attack of atmospheric gases such as Co2,H2S,air and water etc. which make them corrode results in dull appearance of metals.

Their brightness can be restored:
1) by oiling
2) by painting
3) by greasing
4) by electroplating
5) by galvanisation
6) by alloying and
7) by anodizing