Question

Which one of the following is a noble metal?
A. Palladium
B. Titanium
C. Niobium
D. Tantalum

Answer 1

Hint: A noble metal is a type of element which has very less reactivity (almost zero) and does not take part in any form of chemical reaction such as corrosion, oxidation or reduction reactions, etc. A noble metal does not have any chemical activity with the acids and remains as such when it comes in contact with either a strong or a weak acid.

Complete step by step answer: The metals which show resistance towards the corrosion or any form of chemical reactivity come under the category of noble metals. In the periodic table, there are 9 noble metals. They include ruthenium, rhodium, gold, platinum, silver, osmium, mercury, iridium and palladium. There are many other metals which do not undergo corrosion and show noble metals like properties but are not considered as noble metals. They are titanium, niobium, copper and tantalum. These metals are of a great value as they are found in the Earth’s crust and are mostly used in the various metallurgical processes such as extraction of minerals from their respective ores. Many elements like gold, mercury and silver can be dissolved in strong acids such as a mixture of hydrochloric acid and nitric acid, but the noble metals do not get corroded even in such a strong acidic mixture.

Note: The solubility of silver in strong aqua regia mixture is limited by the formation of silver chloride precipitate. Palladium and silver are somehow soluble in nitric acid. Ruthenium can be dissolved in aqua regia only when there is a presence of oxygen. Niobium and tantalum are resistant to all kinds of acids, including aqua regia.