विज्ञान – Science MCQ
विज्ञान – डिप्लोमा प्रवेश
Science · CTEVT Diploma Engineering Entrance · ४११ प्रश्न
४११ प्रश्न उपलब्ध। मोड छान्नुहोस्:
विज्ञान: 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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A heterozygous tall pea plant (Tt) is crossed with another heterozygous tall plant (Tt). The phenotypic ratio of tall to dwarf offspring is:
सही उत्तर: घ) 3 : 1
Tt × Tt gives TT, Tt, Tt, tt; three are tall and one is dwarf. 1 : 2 : 1 is the genotypic ratio of the same cross.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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During electrolysis of acidified water, the volume ratio of hydrogen to oxygen collected is:
सही उत्तर: घ) 2 : 1
Water (H₂O) splits as 2H₂O → 2H₂ + O₂, giving hydrogen and oxygen in a 2 : 1 volume ratio. 8 : 1 is the ratio by mass of oxygen to hydrogen (O : H).
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The molecular formula of an alkane containing 5 carbon atoms is:
सही उत्तर: ग) C₅H₁₂
Alkanes follow CnH2n+2, so for n = 5: C₅H₁₂ (pentane). C₅H₁₀ fits the alkene formula CnH2n.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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10 g of common salt is dissolved in 90 g of water. The mass percentage of salt in the solution is:
सही उत्तर: क) 10%
Mass % = solute/solution × 100 = 10/(10 + 90) × 100 = 10%. 11.1% results from dividing by the mass of water only.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Ammonia gas is collected by downward displacement of air (not over water) because it is:
सही उत्तर: क) Lighter than air and highly soluble in water
Ammonia is lighter than air, so it collects at the top of an inverted jar, and it is very soluble in water, so it cannot be collected over water.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A gas produced by the reaction of zinc with dilute sulphuric acid burns with a 'pop' sound. The gas is:
सही उत्तर: ग) Hydrogen
Zn + H₂SO₄ → ZnSO₄ + H₂; hydrogen burns with a pop sound. Oxygen instead rekindles a glowing splinter.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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When carbon dioxide is passed through lime water, the lime water turns milky due to the formation of:
सही उत्तर: घ) Calcium carbonate
Ca(OH)₂ + CO₂ → CaCO₃ + H₂O; insoluble CaCO₃ makes it milky. Passing excess CO₂ makes it clear again due to soluble calcium bicarbonate.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Temporary hardness of water can be removed simply by boiling because it is caused by:
सही उत्तर: ख) Bicarbonates of calcium and magnesium
On boiling, soluble bicarbonates change into insoluble carbonates that settle down. Chlorides and sulphates cause permanent hardness, which boiling cannot remove.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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An iron nail kept in boiled water covered with a layer of oil does not rust because:
सही उत्तर: ग) Oxygen (air) is not available
Rusting requires both water and oxygen; boiling removes dissolved air and the oil layer stops fresh air from dissolving. Water is present, so that option is wrong.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Which metal does NOT produce hydrogen gas when added to dilute hydrochloric acid?
सही उत्तर: ग) Copper
Copper is below hydrogen in the reactivity series, so it cannot displace hydrogen from dilute acids. Zinc, magnesium and iron are above hydrogen.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
यी अभ्यास प्रश्न हुन्, आधिकारिक प्रश्न होइनन्। पाठ्यक्रम, विज्ञापन र नतिजाका लागि सम्बन्धित निकायको आधिकारिक वेबसाइट हेर्नुहोस्। उत्तरमा गल्ती भेटे प्रश्नमुनिको "टिप्पणी / गल्ती रिपोर्ट" मा लेख्नुहोस्।
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