NEET Free Online Mock Test - 2019

NEET Physics  Thermodynamics  Practice Q & A

1. “Heat cannot by itself flow from a body at lower temperature to a body at higher temperature” is a statement or consequence of

first law of thermodynamics second law of thermodynamics conservation of momentum conservation of mass

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2. Helium gas goes through a cycle ABCDA (consisting of two isochoric and isobaric lines) as shown in figure. Efficiency of this cycle is nearly
(Assume the gas to be close to ideal gas)
helium cycle

15.4% 9.1% 10.5% 12.5%

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3. A Carnot engine, having an efficiency of η =1/10 as heat engine, is used as a refrigerator. If the work done on the system is 10 J, the amount of energy absorbed from the reservoir at lower temperature is

100 J 99 J 90 J 1 J

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4. The specific heat capacity of a metal at low temperature (T) is given as Cp(kJK–1kg–1) = 32$\left(\dfrac{\text{T}}{400}\right)^3$. A 100 gram vessel of this metal is to be cooled from 20 K to 4 K by a special refrigerator operating at room temperature (27°C). The amount of work required to cool the vessel is

Less than 0.028 kJ Equal to 0.002 kJ Greater than 0.148 kJ Between 0.148 kJ and 0.028 kJ

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5. A Carnot engine working between 300 K and 400 K has 800 J of useful work. The amount of heat energy supplied to the engine from the source is

2400 J 3200 J 1200 J 3600 J

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6. Which statement is incorrect?

All reversible cycles have same efficiency. Reversible cycle has more efficiency than an irreversible one. Carnot cycle is a reversible one. Carnot cycle has the maximum efficiency in all cycles.

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7. A refrigerator works between 4°C and 30°C. It is required to remove 600 calories of heat every second in order to keep the temperature of the refrigerated space constant. The power required is [Take 1 cal = 4.2 joules)

236.5 W 2365 W 2.365 W 23.65 W

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8. A Carnot engine, whose efficiency is 40%, takes in heat from a source maintained at a temperature of 500K. It is desired to have an engine of efficiency 60%, then the intake temperature for the same exhaust (sink) temperature must be :

efficiency of Carnot engine cannot be made larger than 50% 1200 K 750 K 600 K

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9. An ideal gas is compressed to half its initial volume by means of several processes. Which of the process results in the maximum work done on the gas?

Isothermal Adiabatic Isobaric Isochoric

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10. Figure below shows two paths that may be taken by a gas to go from a state A to a state C. In process AB, 400 J of heat is added to the system and in process BC, 100 J of heat is added to the system. The heat absorbed by the system in the process AC will be
gas change states

380 J 500 J 460 J 300 J

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