Gold(Au), Silver(Ag), and Platinum Group metals(PGMs) this include Platinum(Pt), Palladium(Pd), Rhodium(Rh), Ruthenium(Ru), Osmium(Os) and Iridium(Ir) all belongs to the category of Noble metals. They are chemically inert and noncorrosive, does not react with most of the acids (chemically inert) and is inactive towards oxygen.