In a working refrigerator, the value of COP is always
0
< 0
< 1
> 1
Correct Answer :
D. > 1
Related Questions
Gibbs free energy per mole for a pure substance is equal to the
Latent heat of vaporisation
Chemical potential
Molal boiling point
Heat capacity
The thermodynamic law, PVy = constant, is not applicable in case of
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Free expansion of an ideal gas
Adiabatic expansion of steam in a turbine
Adiabatic compression of a perfect gas
The equation Tds = dE - PdV applies to
Single phase fluid of varying composition
Single phase fluid of constant composition
Open as well as closed systems
Both (B) and (C)
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Molecular size
Volume
Pressure
Temperature
Linde gas liquefaction process employs cooling
By throttling
By expansion in an engine
At constant pressure
None of these
Internal energy change of a system over one complete cycle in a cyclic process is
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+ve
-ve
Dependent on the path
A cyclic engine exchanges heat with two reservoirs maintained at 100 and 300°C respectively. The maximum work (in J) that can be obtained from 1000 J of heat extracted from the hot reservoir is
349
651
667
1000
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Maxwell's equation
Clausius-Clapeyron Equation
Van Laar equation
Nernst Heat Theorem
Equilibrium constant decreases as the temperature
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Increases, for an endothermic reaction
None of these
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Critical pressure to pressure
Pressure to pseudocritical pressure
Pseudocritical pressure to pressure
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None of these
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Unity
Infinity
None of these
Pick out the wrong statement.
The values of (∂P/∂V)T and (∂2P/∂V2)T are zero for a real gas at its critical point
Heat transferred is equal to the change in the enthalpy of the system, for a constant pressure, non-flow, mechanically reversible process
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During a reversible adiabatic process, the entropy of a substance remains constant
Critical temperature is defined as the temperature above which a gas will
Not liquify (barring exceptions)
Immediately liquify
Never liquify however high the pressure may be
None of these
Refrigerants commonly used for domestic refrigerators are
Ethyl chloride or methyl chloride
Freon-12
Propane
NH3 or CO2
For a constant volume process
dE = CpdT
dE = CvdT
dQ = dE + pdV
dW = pdV
What happens in a reversible adiabatic expansion process?
Heating takes place
Cooling takes place
Pressure is constant
Temperature is constant
Pick out the wrong statement.
Minimum number of degree of freedom of a system is zero
Degree of freedom of a system containing a gaseous mixture of helium, carbon dioxide and hydrogen is 4
For a two phase system in equilibrium made up of four non-reacting chemical species, the number of degrees of freedom is 4
Enthalpy and internal energy change is zero during phase change processes like melting, vaporisation and sublimation
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Triple
Plait
Critical
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Same COP
Decreased COP
Increased or decreased COP; depending upon the type of refrigerant
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5 & 3
3.987 & 1.987
1.987 & 0.66
0.66 & 1.987
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Adiabatic
Isometric
Isentropic
Isothermal
Specific volume of an ideal gas is
Equal to its density
The reciprocal of its density
Proportional to pressure
None of these
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Critical temperature
Melting point
Freezing point
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Formation
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Isobaric
Adiabatic
Isothermal
For a thermodynamic system containing 'x' chemical species, the maximum number of phases that can co-exist at equilibrium is
x
x + 1
x + 2
x + 3
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Entropy
Temperature
Enthalpy
Pressure
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Gibbs-Duhem
Gibbs-Helmholtz
Maxwell's
None of these
In a turbine, the fluid expands almost
Isothermally
Isobarically
Adiabatically
None of these