Out of the following refrigeration cycles, which one has maximum COP?
Air cycle
Carnot cycle
Ordinary vapor compression cycle
Vapor compression with a reversible expansion engine
Correct Answer :
B. Carnot cycle
Related Questions
If two pure liquid constituents are mixed in any proportion to give an ideal solution, there is no change in
Volume
Enthalpy
Both (A) & (B)
Neither (A) nor (B)
Specific heat of a gas for a reversible adiabatic process is
Negative
Zero
Infinity
None of these
Fugacity co-efficient of a substance is the ratio of its fugacity to
Mole fraction
Activity
Pressure
Activity co-efficient
The fugacity of a gas in a mixture is equal to the product of its mole fraction and its fugacity in the pure state at the total pressure of the mixture. This is
The statement as per Gibbs-Helmholtz
Called Lewis-Randall rule
Henry's law
None of these
A system in which there is exchange of energy but not of mass, is called a/an __________ system.
Isolated
Open
Insulated
Closed
Filling of gas from a high pressure cylinder into small bottles is an example of a/an __________ process.
Equilibrium
Adiabatic
Steady
Unsteady
When a system is in equilibrium for all possible processes, the differential or finite change of entropy is
< 0
> 0
= 0
None of these
Entropy of the system decreases, when
Snow melts into water
A gas expands spontaneously from high pressure to low pressure
Water is converted into ice
Both (B) & (C)
Heat pump
Accomplishes only space heating in winter
Accomplishes only space cooling in summer
Accomplishes both (A) and (B)
Works on Carnot cycle
In Joule-Thomson porous plug experiment, the
Enthalpy does not remain constant
Entire apparatus is exposed to surroundings
Temperature remains constant
None of these
Joule-Thomson effect i.e., a throttling process is a constant __________ process.
Entropy
Temperature
Internal energy
Enthalpy
The temperature at the eutectic point of the system is the __________ temperature that can be attained in the system.
Lowest
Highest
Average
None of these
With increase in temperature, the internal energy of a substance
Increases
Decreases
Remains unchanged
May increase or decrease; depends on the substance
Which of the following units is not present in both the vapor compression refrigeration system and absorption refrigeration system?
Expansion valve
Condenser
Refrigerator
Compressor
Chemical potential of ith component of a system is given by
μi = (∂F/∂ni)T, P, ni
μi = (∂A/∂ni)T, P, ni
μi = (∂F/∂ni)T, P
μi = (∂A/∂ni)T, P
Law of corresponding states says that
Two different gases behave similarly, if their reduced properties (i.e. P, V and T) are same
The surface of separation (i. e. the meniscus) between liquid and vapour phase disappears at the critical temperature
No gas can be liquefied above the critical temperature, howsoever high the pressure may be.
The molar heat of energy of gas at constant volume should be nearly constant (about 3 calories)
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)
Pick out the wrong statement.
Cp of monatomic gases such as metallic vapor is about 5 kcal/kg.atom
The heat capacity of solid inorganic substance is exactly equal to the heat capacity of the substance in the molten state
There is an increase in entropy, when a spontaneous change occurs in an isolated system
At absolute zero temperature, the heat capacity for many pure crystalline substances is zero
The expression for entropy change given by, ΔS = nR ln (V2/V1) + nCv ln (T2/T1) is valid for
Reversible isothermal volume change
Heating of a substance
Cooling of a substance
Simultaneous heating and expansion of an ideal gas
At __________ point, all the three phases (i.e. solid, liquid and gas) co-exist.
Eutectic
Triple
Plait
Critical
The rate at which a substance reacts is proportional to its active mass and the rate of a chemical reaction is proportional to the product of active masses of the reacting substances. This is the
Lewis-Randall rule
Statement of Van't Hoff Equation
Le-Chatelier's principle
None of these
Entropy change for an irreversible process taking system and surrounding together is
0
> 0
< 0
None of these
In case of the decomposition of hydroiodic acid (2HI H2 + I2), addition of H2 (at equilibrium condition) will
Increase the partial pressure of I2
Decrease the partial pressure of HI
Diminish the degree of dissociation of HI
None of these
In a P-V diagram (for an ideal gas), an isothermal curve will coincide within adiabatic curve (through a point), when
Cp < Cv
Cp = Cv
Cp > Cv
C ≥ Cv
The specific heat of saturated water vapour at 100°C is
∞
-ve
0
+ve
Degree of freedom of a system consisting of a gaseous mixture of H2 and NH3 will be
0
1
2
3
The necessary and sufficient condition for equilibrium between two phases is
The concentration of each component should be same in the two phases
The temperature of each phase should be same
The pressure should be same in the two phases
The chemical potential of each component should be same in the two phases
Requisites of a reversible process is that the
System and surroundings pressure be equal
Friction in the system should be absent
System and surroundings temperature be equal
None of these
The ammonia synthesis reaction represented by N2 + 3H2 2NH3; ΔH = - 22.4 kcal, is
Endothermic
Exothermic
Isothermal
Adiabatic
Water on heating from 1 to 4°C
Contracts
Expands
Has same volume
May contract or expand