Refrigerants commonly used for domestic refrigerators are
Ethyl chloride or methyl chloride
Freon-12
Propane
NH3 or CO2
Correct Answer :
A. Ethyl chloride or methyl chloride
Related Questions
The co-efficient of performance (COP) of a refrigerating system, which is its index of performance, is defined as the ratio of useful refrigeration to the net work. The units of __________ and COP are the same.
Kinematic viscosity
Work
Temperature
None of these
Which of the following is not an intensive property?
Volume
Density
Temperature
Pressure
For an isothermal process, the internal energy of a gas
Increases
Decreases
Remains unchanged
Data insufficient, can't be predicted
The Maxwell relation derived from the differential expression for the Helmholtz free energy (dA) is
(∂T/∂V)S = - (∂P/∂S)V
(∂S/∂P)T = - (∂V/∂T)P
(∂V/∂S)P = (∂T/∂P)S
(∂S/∂V)T = (∂P/∂T)V
In any spontaneous process, the __________ free energy decreases.
Helmholtz
Gibbs
Both a & b
Neither 'a' nor 'b'
The extensive properties are
Volume, mass and number of moles
Free energy, entropy and enthalpy
Both (A) and (B)
None of these
A gas has a volume of 27.3 c.c. at 0°C. Its volume at 10°C (if pressure remains unchanged) will be __________ c.c.
2.73
28.3
273
283
Pick out the wrong statement:
The expansion of a gas in vacuum is an irreversible process
An isometric process is a constant pressure process
Entropy change for a reversible adiabatic process is zero
Free energy change for a spontaneous process is negative
What is the value of Joule-Thomson co-efficient for an ideal gas?
+ve
-ve
0
∞
Specific/molar Gibbs free energy for a pure substance does not change during
Sublimation
Vaporisation
Melting
Either (A), (B) or (C)
Work done in case of free expansion is
Indeterminate
Zero
Negative
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
The Carnot co-efficient of performance (COP) of a domestic air conditioner compared to a household refrigerator is
Less
More
Same
Dependent on climatic conditions
Which of the following is Virial equation of state?
(p + a/V2)(V - b) = nRT
PV = nRT
PV = A + B/V + C/V2 + D/V3 + ...
None of these
__________ functions are exemplified by heat and work.
Path
Point
State
None of these
Free energy, fugacity and activity co-efficient are all affected by change in the temperature. The fugacity co-efficient of a gas at constant pressure ____with the increase of reduced temperature.
Decreases
Increases
Remains constant
Decreases logarithmically
Enthalpy changes over a constant pressure path are always zero for __________ gas.
Any
A perfect
An easily liquefiable
A real
In vapour compression refrigeration system, if the evaporator temperature and the condenser temperatures are -13°C and 37°C respectively, the Carnot COP will be
5.2
6.2
0.168
Data insufficient, can't be found out
Heat is added at constant pressure in an ideal __________ cycle.
Stirling
Brayton
Rankine
Both (B) and (C)
Which of the following will increase the volume of a real gas by four times?
Doubling the absolute temperature as well as pressure of the gas
Reducing pressure to one fourth at constant temperature
Reducing temperature to one fourth at constant pressure
Reducing the temperature to half and doubling the pressure
At the critical point of a substance
The surface tension vanishes
Liquid and vapour have the same density
There is no distinction between liquid and vapour phases
All (A), (B) and (C)
Gibbs free energy (F) is defined as
F = E - TS
F = H - TS
F = H + TS
F = E + TS
Gibbs free energy at constant pressure and temperature under equilibrium conditions is
∞
0
Maximum
Minimum
In any spontaneous process,
Only F decreases
Only A decreases
Both F and A decreases
Both F and A increase
In the equation, PVn = Constant, if the value of n = 0, then it represents a reversible __________ process.
Isobaric
Isothermal
Isentropic
Isometric
A chemical reaction will occur spontaneously at constant pressure and temperature, if the free energy is
Zero
Positive
Negative
None of these
Gases are cooled in Joule-Thomson expansion, when it is __________ inversion temperature.
Below
At
Above
Either 'b' or 'c'
Claude gas liquefaction process employs cooling
At constant pressure
By throttling
By expansion in an engine
None of these
As the temperature is lowered towards the absolute zero, the value of the quantity (∂ΔF/∂T) approaches
Zero
Unity
Infinity
None of these
In an ideal gas mixture, fugacity of a species is equal to its
Vapor pressure
Partial pressure
Chemical potential
None of these