Question

Why some materials lose their shine and appear dull

Answer 1

Answer:

it is due to the corrosion of their surface.

Eg:-

1. silver corrodes to form a green layer of Ag2S over its surface.
2. iron corrodes to form brownish flaky layer of Fe2O3.xH2O. o er its surface.
3. copper corrodes to form a green layer of CuCO3 over its surface.
4. Aluminium corrodes to form a layer of Al2O3 over its surface.

the Ayer formed after corrosion is dull and I present on the !

material's surface and make it look dull.

the shine can be restores by removing the outer layer of the corroded material.

Note:- corrosion is a surface phenomena so the metal is still shining inside that layer.

HOPE THAT HELPS.

Please Mark It As BrAinLIesT.

Answer 2

Because of rusting and like that is responsible for the materials shine

And some time cotting on them will matter