Which metal is used in the galvanization of iron? 

Zinc 

The correct answer is option 2. Zinc.

Galvanization is a process used to protect iron and steel from corrosion by applying a protective layer of zinc onto their surfaces. Zinc is the metal commonly used for this purpose due to its ability to form a protective barrier that shields the underlying iron or steel from exposure to oxygen and moisture, which are the primary causes of corrosion.

During the galvanization process, the iron or steel substrate is cleaned and then immersed in a bath of molten zinc or subjected to a process known as hot-dip galvanizing. In this process, the iron or steel is dipped into a bath of molten zinc at high temperatures, typically around 450°C (840°F). The zinc bonds to the surface of the iron or steel through a metallurgical reaction, forming a layer of zinc-iron alloy known as galvanized coating or zinc coating.

The galvanized coating acts as a sacrificial anode, meaning that it corrodes preferentially to the underlying iron or steel substrate. This sacrificial protection mechanism helps to prevent the iron or steel from corroding, even if the zinc coating becomes damaged or scratched. Additionally, zinc is a highly reactive metal compared to iron or steel, so it corrodes more readily when exposed to corrosive elements such as moisture and oxygen.

In summary, zinc is used in the galvanization of iron and steel because it forms a protective layer that prevents corrosion and extends the lifespan of the metal. This process is widely used in various industries, including construction, automotive, and manufacturing, to protect metal structures and components from degradation due to environmental exposure.