Which type of metals are likely to corrode at a pH level of 8 or higher?

Amphoteric metals, such as aluminum and zinc, have the unique ability to react with both acids and bases. At a pH level of 8 or higher, which is considered alkaline, these metals can undergo corrosion due to the formation of soluble compounds in basic solutions. This characteristic sets them apart from other types of metals, which may have differing reactivity profiles.

For instance, while reactive metals are generally prone to corrosion in acidic environments, they may not be as susceptible in basic conditions. Noble metals, known for their resistance to corrosion, exhibit minimal reactivity in both acidic and alkaline environments. Alkaline metals, on the other hand, are highly reactive but primarily react with water or moisture rather than in a way that is directly correlated to corrosion at elevated pH levels. Thus, the recognition that amphoteric metals are specifically prone to corrosion in alkaline conditions makes them the correct answer in this context.