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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According to Henry's law, the solubility of a gas in a liquid at constant temperature is proportional to the:
सही उत्तर: क) partial pressure of the gas above the liquid
Henry's law: p = K_H x, so the mole fraction (solubility) of the gas is proportional to its partial pressure.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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In a face-centred cubic lattice of edge length a, the radius r of the atom is related to a by:
सही उत्तर: घ) a = 2√2 r
Atoms touch along the face diagonal: 4r = √2 a, so a = 2√2 r.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Which of the following ionic solids shows the Frenkel defect?
सही उत्तर: ग) AgCl
The Frenkel defect needs a small cation that can move into interstitial sites, as Ag⁺ does in AgCl; NaCl, KCl and CsCl show Schottky defects.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The packing efficiency of a body-centred cubic (bcc) lattice is about:
सही उत्तर: ख) 68%
In bcc, 4r = √3a and there are 2 atoms per cell, giving 2 × (4/3)πr³/a³ ≈ 0.68, i.e. 68%.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A gas cools on adiabatic expansion through a porous plug (Joule–Thomson effect) only if its temperature is:
सही उत्तर: क) below its inversion temperature
Joule–Thomson expansion causes cooling only below the inversion temperature; above it, as for H₂ and He at room temperature, the gas warms.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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In the van der Waals equation (P + an²/V²)(V − nb) = nRT, the constant b accounts for:
सही उत्तर: घ) the finite volume occupied by the gas molecules
b is the excluded volume per mole due to the molecules' own size; a corrects for attraction.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Absolute zero on the Celsius scale is:
सही उत्तर: ग) −273.15 °C
0 K = −273.15 °C, the temperature at which an ideal gas would have zero volume by Charles' law.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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According to the kinetic theory of gases, the average kinetic energy of gas molecules depends only on the:
सही उत्तर: ख) absolute temperature
Average kinetic energy per molecule = (3/2)kT, which depends only on the absolute temperature.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The shape of the triiodide ion (I₃⁻) is:
सही उत्तर: क) linear
The central I has two bond pairs and three lone pairs (sp³d); the lone pairs occupy the equatorial positions, making the ion linear.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The number of σ and π bonds in an ethyne (C₂H₂) molecule are respectively:
सही उत्तर: घ) 3 and 2
There are two C–H σ bonds and one C–C σ bond, and the triple bond also contains two π bonds.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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