Why are noble metals for example Rhodium, Palladium, Platinum, and Iridium largely used in chemical manufacturing as heterogeneous catalyst?

They are also called the noble gases or inert gases. They are virtually unreactive towards other elements or compounds. They are found in trace amounts in the atmosphere. Their elemental form at room temperature is colorless, odorless and monatomic gases. They also have full octet of eight valence electrons in their highest orbitals so they have a very little tendency to gain or lose electrons to form ions or share electrons with other elements in covalent bonds.