Question

What is the most expensive metal on earth?

Answer 1

Hint: Rhodium is the most expensive precious metal on the planet. This element belongs to the d-block of the periodic table.

Complete Step by Step Solution:
It has a silvery-white colour, and a strong, corrosion-resistant character.
It is a non-reactive transition metal.
The d-block of the periodic table includes the elements of the groups 3-12 in which the d orbitals are filled successively in each of the four long periods.
There are primarily three series of transition metals, 3d series (Sc to Zn), 4d series (Y to Cd) and 5d series (La to Hg, excluding Ce to Lu).
Rhodium belongs to the second or 4d series.
A transition element is specified as
the one which has incompletely filled d orbitals in its ground state or any one of its oxidation states.

The main purpose of this element is in automobiles as a catalytic converter. It converts harmful unburned hydrocarbons, carbon monoxide, and nitrogen oxide exhaust emissions into less poisonous gases like carbon dioxide and nitrogen gas.
Due to the inert nature of this metal towards corrosion, it is formed into an alloy with platinum or palladium and is involved in corrosion-protective coatings.
Rhodium is used in jewellery and decorative structures.
It is electroplated on white gold and platinum to provide it with a reflective white surface.

Note: Rhodium is among the six platinum group metals which are platinum, palladium, rhodium, osmium, iridium and ruthenium.
It is also categorised as a noble metal, as it doesn't react with oxygen easily.
It behaves as a good catalyst and is immune to corrosion and oxidation.
Few qualities of the platinum group metals comprise increased melting points and non-toxic nature.