Which of the following alloys is generally less reactive than stainless steels?

Copper-nickel alloys are generally less reactive than stainless steels due to their unique composition and properties. These alloys consist primarily of copper and nickel, which provide resistance to corrosion and oxidation. The presence of nickel enhances this resistance, creating a stable and durable material that is less prone to chemical reactivity in harsh environments compared to many other types of stainless steels.

Stainless steels contain varying amounts of chromium, which significantly enhances their corrosion resistance; however, their reactivity can still be higher than that of copper-nickel alloys under certain conditions. Both materials are considered relatively inert, but copper-nickel alloys exhibit superior performance in chlorinated environments, where stainless steels may suffer from localized corrosion.

Other options, such as steel and bronze, while they provide certain benefits, may not exhibit the same level of chemical stability as copper-nickel alloys. Ionic compounds, depending on their specific nature, can also be quite reactive. Therefore, among the choices provided, copper-nickel stands out as having a generally lower reactivity compared to stainless steels.