SSC CGL 2023 PYQ — Question 36

The correct answer is option 2 i.e. rare earth elements.

Lanthanides are often referred to as "rare earth elements" due to several reasons related to their properties and historical context:

Explanation:

• Chemical Properties: The lanthanides are a series of 15 chemical elements in the periodic table with atomic numbers ranging from 57 to 71, from lanthanum through to lutetium. These elements are known for their similar chemical properties, including their high magnetic susceptibility and the ability to form trivalent cations.
• Historical Context: The term "rare earth" originated in the 19th century when these elements were first discovered. At that time, they were found in small quantities and were relatively difficult to separate from other elements, making them appear rare. The "earth" in their name comes from the old term for oxides of elements, which were thought to be oxides of the earth.

 

• Abundance and Distribution: Despite their name, lanthanides are not particularly rare in the Earth's crust. They are relatively abundant, though they are often dispersed and not found in concentrated forms. Their rarity is more about their occurrence in specific mineral deposits and the complexity of their extraction and separation.

 

• Industrial and Technological Use: Lanthanides are crucial in modern technology. They are used in various high-tech applications, including magnets, phosphors in LED lights, catalysts in petroleum refining, and materials in electronic devices. This technological importance contrasts with their historical rarity, as their demand has surged despite their relatively abundant natural presence.

Thus, while lanthanides are not truly rare in the Earth's crust, their historical scarcity, complex extraction processes, and essential role in modern technology contribute to their designation as "rare earth elements."