Which is a more active metal?

The answer indicates that a corroded steel in fresh water is a more active metal. In the context of corrosion and electrochemical activity, the term "active metal" refers to a metal that tends to oxidize more easily, losing electrons and participating in corrosion reactions.

Corroded steel typically has exposed iron, a metal that is chemically more reactive than copper. When steel has corroded, it reveals fresh iron surfaces that are prone to further oxidation, especially in an aqueous environment like fresh water. This environment can facilitate electrochemical reactions, making corroded steel a more active metal overall.

In contrast, a copper rod in copper sulfate solution or a copper sheet in fresh water involves copper, which is less reactive than iron. While copper can undergo corrosion processes, it does not oxidize as readily as iron found in steel. Similarly, new steel in fresh water, while reactive, does not have the same level of exposed active sites as corroded steel, making it less active compared to the corroded state.

Therefore, the characteristic of corroded steel being a more active metal arises from its propensity to participate in oxidation and reduction reactions, especially when in contact with an electrolyte such as fresh water.