The reactivity of metals like zinc, iron, copper, and lead can be determined by observing their reactions with various reagents or solutions, such as acids or displacement reactions with more reactive metals.

The thick oxide layer formed during anodising can be easily dyed, allowing aluminum articles to be colored in various shades. This capability to dye the oxide layer gives aluminum articles an attractive finish, enhancing their aesthetic appeal.

In anodising, a clean aluminum article is made the anode and is electrolysed with dilute sulfuric acid. Oxygen gas is evolved at the anode and reacts with aluminum to form a thicker protective oxide layer.

Aluminum naturally develops a thin oxide layer when exposed to air, which acts as a protective barrier, making it resistant to further corrosion.

Anodising is a process of forming a thick oxide layer on the surface of aluminum. Its purpose is to enhance the corrosion resistance of aluminum and provide a durable and attractive finish.