रसायन विज्ञान (Chemistry) – Chemistry MCQ
रसायन विज्ञान (Chemistry) – इन्जिनियरिङ प्रवेश
Chemistry · Engineering Entrance – Mathematics, Physics, Chemistry & English · ७२८ प्रश्न
७२८ 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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Atoms of different elements having the same mass number, such as ⁴⁰Ar and ⁴⁰Ca, are called:
सही उत्तर: ग) isobars
Isobars have the same mass number but different atomic numbers.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The number of neutrons in a nucleus of ²³⁸₉₂U is:
सही उत्तर: क) 146
Neutrons = A − Z = 238 − 92 = 146.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Under the same conditions of temperature and pressure, the volume of NH₃ formed from 3 L of H₂ with excess N₂ is:
सही उत्तर: ख) 2 L
N₂ + 3H₂ → 2NH₃; by Gay-Lussac's law of gaseous volumes, 3 L H₂ gives 2 L NH₃.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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100 mL of 2 M HCl is diluted with water to 500 mL. The molarity of the diluted solution is:
सही उत्तर: घ) 0.4 M
M₁V₁ = M₂V₂: 2 × 100 = M₂ × 500, so M₂ = 0.4 M.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A solution contains 1 mol of urea dissolved in 9 mol of water. The mole fraction of urea is:
सही उत्तर: घ) 0.1
x = 1/(1 + 9) = 0.1.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Carbon forms two oxides, CO and CO₂, in which the masses of oxygen combining with a fixed mass of carbon are in the ratio 1 : 2. This illustrates the law of:
सही उत्तर: ख) multiple proportions
When two elements form more than one compound, the masses of one combining with a fixed mass of the other are in a simple whole-number ratio.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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When 10 g of H₂ is allowed to react with 64 g of O₂, the maximum mass of water that can be formed is:
सही उत्तर: ग) 72 g
64 g O₂ = 2 mol, which needs 4 mol (8 g) H₂; O₂ is limiting and gives 4 mol H₂O = 72 g.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The number of atoms present in 4 g of helium gas (He = 4) is about:
सही उत्तर: क) 6.022 × 10²³
4 g of He is 1 mol, and helium is monatomic, so it contains N_A ≈ 6.022 × 10²³ atoms.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A current passed through a silver nitrate solution deposits silver at the cathode. The mass of silver deposited by 9650 C of electricity is (Ag = 108, F = 96 500 C mol⁻¹):
सही उत्तर: घ) 10.8 g
9650 C = 0.1 F, which deposits 0.1 mol Ag⁺ → 0.1 × 108 = 10.8 g of silver.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The monomer of Teflon is:
सही उत्तर: ख) tetrafluoroethene
Teflon (PTFE) is formed by addition polymerisation of CF₂=CF₂.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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