Question

ᴇxᴘʟᴀɪɴ ᴡʜʏ sᴜʀғᴀᴄᴇ ᴏғ sᴏᴍᴇ ᴍᴇᴛᴀʟs ᴀᴄϙᴜɪʀᴇ ᴀ ᴅᴜʟʟ ᴀᴘᴘᴇᴀʀᴀɴᴄᴇ ᴡʜᴇɴ ᴇxᴘᴏsᴇᴅ ᴛᴏ ᴀɪʀ ғᴏʀ ᴀ ʟᴏɴɢ ᴛɪᴍᴇ..​

Answer 1

Those metals whose surface acquire a dull appearance are Copper....

It happens because being reactive it reacts with substances present in the atmosphere and forms an outer layer above the surface.

Answer 2

Hey mate,.

It's because of the process - corrosion.

Where the surface area of an object gets faded when it gets oxide with atmospheric air.

Hope it will help you

✌️sai