Question map
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?
Explanation
The correct answer is option A because both statements are factually correct and Statement II provides the scientific basis for Statement I.
Rare earth elements like europium, terbium, and yttrium are used in screen phosphors and backlights[1], confirming Statement I. Rare earth elements like europium and terbium exhibit phosphorescent and fluorescent properties, used in display technologies[2], confirming Statement II.
The key relationship is that Statement II explains WHY Statement I is true. The phosphorescent and fluorescent properties of these rare earth elements are precisely the reason they are utilized in manufacturing flat screens and computer monitors. These elements emit light when excited by energy, making them ideal for display technologies. The phosphorescent properties are not just a coincidental characteristic but the fundamental explanation for their application in screen manufacturing.
Therefore, both statements are correct and Statement II directly explains Statement I, making option A the right choice.
SourcesPROVENANCE & STUDY PATTERN
Guest previewThis is a classic 'Applied Science' question. It moves beyond the periodic table to 'Daily Life Technology.' While standard books like NCERT mention metals in phones generally, the specific link between Rare Earths (REEs) and 'phosphorescence in screens' is a Current Affairs theme driven by the 'Critical Minerals' narrative.
This question can be broken into the following sub-statements. Tap a statement sentence to jump into its detailed analysis.
- Directly names specific rare-earth elements used in display technology.
- Links those elements to screen components (phosphors and backlights) relevant to flat-panel TVs and monitors.
- Affirms that rare earth elements are used in manufacturing screens, supporting the general claim.
- Serves as a corroborating source that the application to screens/monitors is recognized in multiple places.
Gives an example list of many elements used in manufacturing a mobile phone including its screen, showing that screens commonly incorporate a variety of metals (e.g., aluminium, copper, silicon, cobalt, lithium, gold, silver).
A student could take this pattern (screens use conductive and optical metals/semiconductors) and check which of those (or similar) are classified as rare earths to see if any overlap with flat-panel displays.
Specifically notes lead is used in glass panels and gaskets in computer monitors, illustrating that display glass and related components contain heavy metals.
Use this as a precedent that display glass contains specialized metals and then compare to lists of rare earths used in display phosphors or components (e.g., yttrium, europium) to evaluate plausibility.
Mentions policy measure to reduce customs duty on parts of open cells of TV panels, implying TV panels are distinct manufactured components with specialized inputs.
Treat this as evidence panels have specific inputs; a student could look up typical panel component lists (glass, backlight, phosphors, semiconductors) and then test which rare earths are used in those subcomponents.
States many special metals are important for modern technologies and are used/recycled, signaling that advanced electronics (including displays) commonly use specialized metals.
Combine this general rule with a catalogue of modern display materials to narrow which specialized (possibly rare earth) metals are likely to be present in flat-panel screens.
Describes manganese's use to impart properties to alloys and mentions its industrial importance, illustrating the broader pattern that specific elements are chosen for particular functional properties in manufacturing.
Apply this pattern to displays: identify the functional needs of flat panels (luminescence, magnetism, conductivity) and then check which rare earths provide those functions (e.g., rare-earth phosphors for color/luminescence).
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