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Which of the following has the minimum value of COP for a given refrigeration effect?

A. Reverse Carnot cycle

B. Ordinary vapour-compression cycle

C. Vapour-compression process with a reversible expansion engine

D. Air refrigeration cycle

Correct Answer :

D. Air refrigeration cycle


Related Questions

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The chemical potential for a pure substance is __________ its partial molal free energy.

A. More than

B. Less than

C. Equal to

D. Not related to

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A gas shows deviation from ideal behaviour at

A. Low pressure and high temperature

B. Low pressure and low temperature

C. Low temperature and high pressure

D. High temperature and high pressure

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4

The number of degrees of freedom at the triple point of water is

A. 0

B. 1

C. 2

D. 3

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Boiling of liquid is accompanied with increase in the

A. Vapor pressure

B. Specific Gibbs free energy

C. Specific entropy

D. All (A), (B) and (C)

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The most important application of distribution law is in

A. Evaporation

B. Liquid extraction

C. Drying

D. Distillation

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Enthalpy 'H' is defined as

A. H = E - PV

B. H = F - TS

C. H - E = PV

D. None of these

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Which is not a refrigerant?

A. SO2

B. NH3

C. CCl2F2

D. C2H4Cl2

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Pick out the correct statement.

A. Entropy and enthalpy are path functions

B. In a closed system, the energy can be exchanged with the surrounding, while matter cannot be exchanged

C. All the natural processes are reversible in nature

D. Work is a state function

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For water at 300°C, it has a vapour pressure 8592.7 kPa and fugacity 6738.9 kPa Under these conditions, one mole of water in liquid phase has a volume of 25.28 cm3 and that in vapour phase in 391.1 cm3.Fugacity of water (in kPa) at 9000 kPa will be

A. 6738.9

B. 6753.5

C. 7058.3

D. 9000

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If different processes are used to bring about the same chemical reaction, the enthalpy change is same for all of them. This is __________ law.

A. Hess's

B. Kirchoff's

C. Lavoisier and Laplace

D. None of these

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An ideal monatomic gas is taken round the cycle ABCDA as shown below in the P-V diagram. The work done during the cycle is

A. PV

B. 2PV

C. PV/2

D. 0

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Melting of ice is an example of an __________ process.

A. Adiabatic

B. Isothermal

C. Isometric

D. None of these

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The adiabatic throttling process of a perfect gas is one of constant enthalpy

A. In which there is a temperature drop

B. Which is exemplified by a non-steady flow expansion

C. Which can be performed in a pipe with a constriction

D. In which there is an increase in temperature

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The first law of thermodynamics is a restatement of the law of conservation of

A. Mass

B. Energy

C. Momentum

D. None of these

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The shape of T-S diagram for Carnot Cycle is a

A. Rectangle

B. Rhombus

C. Trapezoid

D. Circle

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During adiabatic expansion of gas

A. Pressure remains constant

B. Pressure is increased

C. Temperature remains constant

D. None of these

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A closed system is cooled reversibly from 100°C to 50°C. If no work is done on the system

A. its internal energy (U) decreases and its entropy (S) increases

B. U and S both decreases

C. U decreases but S is constant

D. U is constant but S decreases

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Ideal gas law is applicable at

A. Low T, low P

B. High T, high P

C. Low T, high P

D. High T, low P

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What is the degree of freedom for a system comprising liquid water equilibrium with its vapour?

A. 0

B. 1

C. 2

D. 3

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During Joule-Thomson expansion of gases

A. Enthalpy remains constant

B. Entropy remains constant

C. Temperature remains constant

D. None of these

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The Maxwell relation derived from the differential expression for the Helmholtz free energy (dA) is

A. (∂T/∂V)S = - (∂P/∂S)V

B. (∂S/∂P)T = - (∂V/∂T)P

C. (∂V/∂S)P = (∂T/∂P)S

D. (∂S/∂V)T = (∂P/∂T)V

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For an ideal gas, the activity co-efficient is

A. Directly proportional to pressure

B. Inversely proportional to pressure

C. Unity at all pressures

D. None of these

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In reactions involving solids and liquids (where change in volume is negligible), the heat of reaction at constant pressure as compared to that at constant volume is

A. More

B. Less

C. Same

D. Unpredictable; depends on the particular reaction

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The intensive properties are

A. Molar volume, density, viscosity and boiling point

B. Refractive index and surface tension

C. Both (A) and (B)

D. None of these

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On opening the door of an operating refrigerator kept in a closed room, the temperature of the room will

A. Increase

B. Decrease

C. Remain same

D. Increase in summer and will decrease in winter

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In any spontaneous process, the __________ free energy decreases.

A. Helmholtz

B. Gibbs

C. Both a & b

D. Neither 'a' nor 'b'

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Clapeyron Equation deals with the

A. Rate of change of vapour pressure with temperature

B. Effect of an inert gas on vapour pressure

C. Calculation of ΔF for spontaneous phase change

D. Temperature dependence of heat of phase transition

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What is the ratio of adiabatic compressibility to isothermal compressibility?

A. 1

B. < 1

C. > 1

D. >> 1

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What is the value of Joule-Thomson co-efficient for an ideal gas?

A. +ve

B. -ve

C. 0

D.

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Linde gas liquefaction process employs cooling

A. By throttling

B. By expansion in an engine

C. At constant pressure

D. None of these