Consider the following statements:Statement I: Some rare earth elements are used in the manufacture

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Question

Consider the following statements:Statement I: Some rare earth elements are used in the manufacture of flat television screens and computer monitors.Statement II: Some rare earth elements have phosphorescent properties.Which one of the following is correct in respect of the above statements?

Accepted Answer

Correct Answer: B — Both Statements are correct but Statement II does not explain Statement IStep-by-step Solution:Statement I — Rare earth elements used in flat TV screens and computer monitors: This is correct. Rare earth elements (REEs) are critical components in modern display technologies. Specifically: Europium (Eu) — red phosphor in older CRT screens and LEDs; Terbium (Tb) — green phosphor; Yttrium (Y) — component of red/green phosphors and LED phosphors; Cerium (Ce) — used in polishing glass for LCD screens. In modern LED-backlit LCD screens and OLED displays, REE-based phosphors are used to produce accurate colour rendition. ✓Statement II — Some rare earth elements have phosphorescent properties: This is correct. Phosphorescence is the ability to absorb energy (light/radiation) and re-emit it as visible light, sometimes for extended periods after the source is removed. Several rare earth elements have this property. Europium, Terbium, Erbium, and Dysprosium are well-known for their luminescent (fluorescent and phosphorescent) properties due to the unique electronic structure of their 4f electron shells. ✓Does Statement II explain Statement I? Not directly. The phosphorescent properties of REEs (Statement II) are a general physical property, not the specific reason REEs are used in flat screens and monitors. Modern flat screens use REEs primarily as phosphors in LED backlights and as components in various electronic components — the phosphorescent property is relevant to some applications but does not fully explain all uses of REEs in flat screens (e.g., cerium's use as a polishing agent). The two statements are both correct but the relationship is not a direct causal explanation. ✗ (II does not explain I)Why other options are incorrect:Option A: Incorrect. While both are correct, Statement II (phosphorescent properties in general) does not specifically explain Statement I (use in flat screens) — the phosphorescent property is one of several reasons, not the complete explanation.Option C: Incorrect. Statement II is correct — REEs do have phosphorescent properties.Option D: Incorrect. Statement I is correct — REEs are indeed used in flat screens.Key Concept: Rare Earth Elements (REEs): Group of 17 elements — 15 lanthanides (La to Lu) + Sc and Y. Critical for: Magnets (Neodymium, Dysprosium — in EV motors, wind turbines), Phosphors for displays (Europium, Terbium, Cerium), Catalysts, Optical fibres, Battery technologies. China produces ~60% of global REEs and controls ~80% of processing. India's REE reserves: Monazite sands in Kerala, Tamil Nadu, Odisha contain significant REEs + thorium. Indian Rare Earths Ltd (IREL) — state enterprise for REE production. Critical Minerals: India identified REEs as critical minerals in its 2023 list. India-Australia-USA cooperation on REE supply chains. Phosphorescence vs Fluorescence: Fluorescence — emission stops immediately when excitation source removed; Phosphorescence — emission continues (sometimes for hours) after source removed. REEs used in 'glow-in-the-dark' materials.

Consider the following statements:Statement I: Some rare earth elements are used in the manufacture of flat television screens and computer monitors.Statement II: Some rare earth elements have phosphorescent properties.Which one of the following is correct in respect of the above statements?

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Consider the following statements:Statement I: Some rare earth elements are used in the manufacture of flat television screens and computer monitors.Statement II: Some rare earth elements have phosphorescent properties.Which one of the following is correct in respect of the above statements?

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