Explanation

Rare Earth Elements (REEs) are a group of 17 chemically similar elements — the 15 lanthanides along with scandium and yttrium. Despite their name, they are not particularly rare in the Earth’s crust, but they are difficult to extract due to their low concentrations and dispersed occurrence. They possess unique magnetic, luminescent, and electrochemical properties, making them indispensable in modern technology.

Statement I is correct. Rare earth elements such as europium, terbium, and yttrium are extensively used in the production of phosphors for display technologies — including flat-screen televisions and computer monitors. These phosphors emit specific colours when excited by electrons: europium produces red, terbium produces green, and yttrium serves as a host lattice that enhances the efficiency of these phosphors. Together, they enable the vivid colour displays seen in modern screens.

Statement II is correct and directly explains Statement I. Several rare earth elements exhibit phosphorescence — a form of photoluminescence where a material absorbs energy and then emits light. Elements like europium and terbium are especially known for this property. It is precisely this ability to emit light upon excitation that makes them suitable for use as phosphors in display screens. Statement II therefore provides the underlying scientific reason for the application described in Statement I.