भौतिक विज्ञान (Physics) – Physics MCQ
भौतिक विज्ञान (Physics) – इन्जिनियरिङ प्रवेश
Physics · Engineering Entrance – Mathematics, Physics, Chemistry & English · १,३९८ प्रश्न
१,३९८ प्रश्न उपलब्ध। मोड छान्नुहोस्:
भौतिक विज्ञान (Physics): 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 molar specific heat at constant volume of a monatomic ideal gas is:
सही उत्तर: क) 3R/2
A monatomic gas has 3 translational degrees of freedom, U = (3/2)RT per mole, so C_v = 3R/2.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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According to the kinetic theory, the pressure exerted by an ideal gas of density ρ and rms speed v_rms is:
सही उत्तर: घ) (1/3)ρv_rms²
From kinetic theory P = (1/3)ρv_rms².
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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For a reversible adiabatic process of an ideal gas, which of the following remains constant?
सही उत्तर: ग) TV^(γ − 1)
Combining PV^γ = constant with PV = nRT gives TV^(γ − 1) = constant.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A heat engine absorbs 1000 J from the source and rejects 600 J to the sink per cycle. Its efficiency is:
सही उत्तर: ख) 40%
η = W/Q₁ = (1000 − 600)/1000 = 0.4 = 40%.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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When an ideal gas undergoes free expansion into a vacuum in an insulated container, its temperature:
सही उत्तर: क) remains unchanged
In free expansion Q = 0 and W = 0, so ΔU = 0; for an ideal gas U depends only on T, so T is unchanged.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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In an isochoric (constant volume) process, the work done by the gas is:
सही उत्तर: घ) zero
W = ∫P dV and dV = 0, so no work is done; all heat supplied changes the internal energy.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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According to Kirchhoff's law of thermal radiation, at a given temperature:
सही उत्तर: ग) good absorbers are good emitters
The ratio of emissive power to absorptive power is the same for all bodies at a given temperature, so good absorbers are good emitters.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A copper rod (K = 400 W m⁻¹ K⁻¹) of length 1 m and cross-section 1 cm² has its ends at 100 °C and 0 °C. The rate of heat flow through it is:
सही उत्तर: ख) 4 W
H = KAΔT/L = 400 × 10⁻⁴ × 100/1 = 4 W.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The triple point of water, used as the fixed point of the Kelvin scale, is:
सही उत्तर: क) 273.16 K
The triple point of water (where ice, water and vapour coexist) is assigned exactly 273.16 K; 273.15 K corresponds to 0 °C.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The heat needed to raise the temperature of 2 kg of water by 10 °C is (specific heat of water = 4200 J kg⁻¹ K⁻¹):
सही उत्तर: घ) 84000 J
Q = mcΔT = 2 × 4200 × 10 = 84000 J.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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