Mark the correct statement.
a) Metals lose their lustre on keeping in air.
b) Gold is lustrous.
c) Metals are lustrous and can be polished.

The correct option is D All the statements are correct.
Metals lose their lustre when kept exposed to air for a long time and get a dull appearance.
Gold is known for its lustrous yellow appearance.
Lustre is a property of metals and metals can be polished to increase their metallic lustre.

Hence, all the statements are correct.