Which elements are considered noble metals?

• A. Pd, Ag, Os, Ir, Pt, Au
• B. H, He, Ne, Ar
• C. Fe, Ni, Co, Cu
• D. Al, Mg, Ca, Na

Answer: (A)

Noble metals are metals that resist corrosion and oxidation, staying shiny and stable in air and water. The six elements palladium, silver, osmium, iridium, platinum, and gold fit this description because they are highly resistant to tarnish and corrosion and often occur in their native metallic form. The other groups don’t fit because the second group contains noble gases, which are nonmetals and not metals at all. The third group includes common transition metals like iron, nickel, cobalt, and copper, which can oxidize or corrode under normal conditions. The fourth group contains highly reactive metals such as aluminum, magnesium, calcium, and sodium, which readily form oxides. So the set with palladium, silver, osmium, iridium, platinum, and gold are the noble metals.