Which type of metal is considered corrosive in a highly alkaline environment?

Amphoteric metals are unique in that they can react with both acids and bases. In a highly alkaline environment, amphoteric metals exhibit corrosive behavior because they can engage in reactions with hydroxide ions present in the alkaline solution. This results in the formation of soluble metal hydroxides, leading to accelerated degradation of the metal.

For example, aluminum is an amphoteric metal that, when exposed to a strong base like sodium hydroxide, will react to form soluble aluminate ions, thus experiencing significant corrosion. Other metals classified as amphoteric also follow this behavior under similar conditions, making them susceptible to corrosion in highly alkaline environments.

In contrast, other options like copper are generally resistant to corrosion in alkaline conditions, and symphoteric metals and carbon do not exhibit the same reactivity with bases that amphoteric metals do.