रसायन विज्ञान (Chemistry) – Chemistry MCQ
रसायन विज्ञान (Chemistry) – CEE प्रवेश
Chemistry · Medical Entrance (CEE) – Physics, Chemistry, Biology & MAT · ४१० प्रश्न
४१० प्रश्न उपलब्ध। मोड छान्नुहोस्:
रसायन विज्ञान (Chemistry): प्रश्न र उत्तर
सही लागेको विकल्पमा थिच्नुहोस्। सही भए हरियो, गलत भए रातो देखिन्छ; ३ सेकेन्डपछि सही उत्तर र व्याख्या देखिन्छ।
सही: ० / ०
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The most abundant noble gas in Earth's atmosphere is:
सही उत्तर: घ) Argon
Argon makes up nearly 1% of dry air, far more than any other noble gas. Helium is abundant in the universe but scarce in the atmosphere because it escapes into space.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The catalyst used in the Contact process for the manufacture of sulphuric acid is:
सही उत्तर: क) V₂O₅
Vanadium pentoxide catalyses the oxidation of SO₂ to SO₃, the key step of the Contact process. Iron is the catalyst in the Haber process.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The catalyst used in the Haber process for the manufacture of ammonia is:
सही उत्तर: क) Iron (with molybdenum as promoter)
Finely divided iron with Mo (or K₂O/Al₂O₃) promoters catalyses N₂ + 3H₂ ⇌ 2NH₃. V₂O₅ is used in the Contact process for sulphuric acid.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The allotrope of carbon that is a good conductor of electricity is:
सही उत्तर: ख) Graphite
In graphite each carbon is sp² hybridised, leaving one delocalised electron per atom that moves between layers to conduct electricity. In diamond all four electrons form sp³ σ bonds, so it is an insulator.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The chemical name of bleaching powder is commonly given as:
सही उत्तर: ग) Calcium oxychloride, Ca(OCl)Cl
Bleaching powder, made by passing chlorine over dry slaked lime, is represented as Ca(OCl)Cl (CaOCl₂). It releases chlorine, which acts as a bleach and disinfectant.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Sodium carbonate is manufactured industrially by the:
सही उत्तर: ख) Solvay (ammonia–soda) process
The Solvay process uses brine, ammonia and CO₂ to form NaHCO₃, which is heated to give Na₂CO₃. The Castner–Kellner process is used for making NaOH.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The chemical formula of Plaster of Paris is:
सही उत्तर: क) CaSO₄·½H₂O
Plaster of Paris is calcium sulphate hemihydrate; mixed with water it sets back into gypsum, CaSO₄·2H₂O. Anhydrous CaSO₄ is called dead-burnt plaster.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Heavy water (D₂O) is used in nuclear reactors as a:
सही उत्तर: ख) Moderator
D₂O slows down fast neutrons without absorbing many of them, so it acts as a moderator. Neutron-absorbing materials like cadmium or boron are used in control rods.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Temporary hardness of water is due to the presence of:
सही उत्तर: क) Bicarbonates of calcium and magnesium
Ca(HCO₃)₂ and Mg(HCO₃)₂ decompose on boiling into insoluble carbonates, so the hardness can be removed by boiling. Chlorides and sulphates cause permanent hardness.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Physical adsorption (physisorption) of a gas on a solid:
सही उत्तर: ग) Decreases with increase in temperature
Physisorption is exothermic and held by weak van der Waals forces, so it decreases as temperature rises. Chemisorption involves chemical bond formation and is usually irreversible.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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