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4

Co-efficient of Performance (COP) of a refrigerator is the ratio of the

A. Work required to refrigeration obtained

B. Refrigeration obtained to the work required

C. Lower to higher temperature

D. Higher to lower temperature

Correct Answer :

B. Refrigeration obtained to the work required


Related Questions

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4

If the pressure on 100 c.c. of air is halved, then its volume (at the same temperature) would be __________ c.c.

A. 100

B. 50

C. 205

D. 200

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4

What is the degree of freedom for two miscible (non-reacting) substances in vapor-liquid equilibrium forming an azeotrope?

A. 0

B. 1

C. 2

D. 3

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4

The compressibility factor for an ideal gas is 1. Its value for any other real gas is

A. 1

B. < 1

C. > 1

D. Either (B) or (C), depends on the nature of the gas

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4

The equation, PV = nRT, is best obeyed by gases at

A. Low pressure & high temperature

B. High pressure & low temperature

C. Low pressure & low temperature

D. None of these

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4

An ideal liquid refrigerant should

A. Not have a sub-atmospheric vapour pressure at the temperature in the refrigerator coils

B. Not have unduly high vapour pressure at the condenser temperature

C. Both (A) and (B)

D. Have low specific heat

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4

The energy of activation of exothermic reaction is

A. Zero

B. Negative

C. Very large compared to that for endothermic reaction

D. Not possible to predict

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4

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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4

Number of degrees of freedom for a three phase system in equilibrium comprising of three nonreacting chemical species is

A. 2

B. 0

C. 1

D. 3

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4

Absolute zero temperature signifies the

A. Minimum temperature attainable

B. Temperature of the heat reservoir to which a Carnot engine rejects all the heat that is taken in

C. Temperature of the heat reservoir to which a Carnot engine rejects no heat

D. None of these

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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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4

Which of the following equations is obtained on combining 1st and 2nd law of thermodynamics, for a system of constant mass?

A. dE = Tds - PdV

B. dQ = CvdT + PdV

C. dQ = CpdT + Vdp

D. Tds = dE - PdV

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4

Entropy of an ideal gas depends upon its

A. Pressure

B. Temperature

C. Both (A) & (B)

D. Neither (A) nor (B)

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4

Compressibility factor (i.e., the ratio of actual volume of gas to the volume predicted by ideal gas law) for all gases are

A. Always greater than one

B. Same at the same reduced temperature

C. Same at the same reduced pressure

D. Both (B) & (C)

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4

Air enters an adiabatic compressor at 300K. The exit temperature for a compression ratio of 3, assuming air to be an ideal gas (Y = Cp/Cv = 7/5) and the process to be reversible, is

A. 300 × (32/7)

B. 300 × (33/5)

C. 300 × (333/7)

D. 300 × (35/7)

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4

Enthalpy changes over a constant pressure path are always zero for __________ gas.

A. Any

B. A perfect

C. An easily liquefiable

D. A real

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4

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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4

Activity co-efficient is a measure of the

A. Departure from ideal solution behaviour

B. Departure of gas phase from ideal gas law

C. Vapour pressure of liquid

D. None of these

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4

The partial pressure of each constituent present in an alloy is __________ the total vapor pressure exerted by the alloy.

A. Less than

B. Equal to

C. More than

D. Either (B) or (C); depends on the type of alloy

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4

Gases are cooled in Joule-Thomson expansion, when it is __________ inversion temperature.

A. Below

B. At

C. Above

D. Either 'b' or 'c'

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4

An irreversible process

A. Is the analog of linear frictionless motion in machines

B. Is an idealised visualisation of behaviour of a system

C. Yields the maximum amount of work

D. Yields an amount of work less than that of a reversible process

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4

The following heat engine produces power of 100,000 kW. The heat engine operates between 800 K and 300 K. It has a thermal efficiency equal to 50% of that of the Carnot engine for the same temperature. The rate at which heat is absorbed from the hot reservoir is

A. 100,000 kW

B. 160,000 kW

C. 200,000 kW

D. 320,000 kW

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4

A liquid under pressure greater than its vapour pressure for the temperature involved is called a __________ liquid.

A. Sub-cooled

B. Saturated

C. Non-solidifiable

D. None of these

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4

Number of phases in a colloidal system is:

A. 1

B. 2

C. 3

D. 4

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4

Pick out the wrong statement.

A. The values of (∂P/∂V)T and (∂2P/∂V2)T are zero for a real gas at its critical point

B. Heat transferred is equal to the change in the enthalpy of the system, for a constant pressure, non-flow, mechanically reversible process

C. Thermal efficiency of a Carnot engine depends upon the properties of the working fluid besides the source & sink temperatures

D. During a reversible adiabatic process, the entropy of a substance remains constant

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4

Gibbs-Helmholtz equation is

A. ΔF = ΔH + T [∂(ΔF)/∂T]P

B. ΔF = ΔH - TΔT

C. d(E - TS) T, V < 0

D. dP/dT = ΔHvap/T.ΔVvap

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4

Free energy changes for two reaction mechanism 'X' and 'Y are respectively - 15 and - 5 units. It implies that X is

A. Slower than Y

B. Faster than Y

C. Three times slower than Y

D. Three times faster than Y

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4

Tea kept in a thermos flask is vigorously shaken. If the tea is considered as a system, then its temperature will

A. Increase

B. Decrease

C. Remain unchanged

D. First fall and then rise

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4

Pick out the correct statement.

A. Compression ratio of an Otto engine is comparatively higher than a diesel engine

B. Efficiency of an Otto engine is higher than that of a diesel engine for the same compression ratio

C. Otto engine efficiency decreases with the rise in compression ratio, due to decrease in work produced per quantity of heat

D. Diesel engine normally operates at lower compression ratio than an Otto engine for an equal output of work

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4

An isentropic process is carried out at constant

A. Volume

B. Pressure

C. Temperature

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

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4

The unity of Planck's constant 'h' in the equation, E = hv is

A. J/s

B. J.S

C. J/kmol

D. kmol/J