Which metal, if coated onto iron, would prevent the corrosion of iron? (a) Zn (b) Sn (c) Mn

Cathodic protection is a corrosion prevention method that's commonly used with metals. It works on the principle of making the protected metal (in this case iron) the cathode of an electrochemical cell. A more easily corroded 'sacrificial metal' acts as the anode, corroding in place of the iron.

Think of cathodic protection like a bodyguard for metals. It's a way to guard important structures like pipelines, ships, and storage tanks from the ever-present threat of rust and corrosion. By providing an alternative target for the corrosive effects of the environment, the iron can remain unscathed and continue its sturdy service for years to come.

The reactivity series of metals is like a leaderboard that ranks metals by their willingness to participate in chemical reactions. It's particularly handy when we're trying to predict possible reactions, especially in the context of preventing corrosion.

This series places the more 'eager' metals that readily give up their electrons and corrode or react, higher up the list, while the more 'reluctant' ones that hold onto their electrons for dear life are found towards the bottom. In corrosion protection, we look towards the higher-ranking, valiant metals to sacrifice themselves and protect the less reactive, more valuable metals from corroding.

A sacrificial anode is the unsung hero in the battle against corrosion. Crafted from a metal higher in the reactivity series than the metal it's protecting, this selfless component willingly succumbs to corrosion, hence the name 'sacrificial'.

The chosen metal, like zinc in our case, offers itself up to be attacked by water, salts, and other corrosive agents, preserving structures of less reactive metals like iron in the process. It's a prime example of a chemical 'sacrifice play', where the anode gradually degrades over time, ensuring the integrity and longevity of the iron it protects. Regular checks and replacements of the sacrificial anode are necessary to maintain continuous protection.