A two stage compressor is used to compress an ideal gas. The gas is cooled to the initial temperature after each stage. The intermediate pressure for the minimum total work requirement should be equal to the __________ mean of P1 and P2. (where, P1 and P2 are initial and final pressures respectively)
Logarithmic
Arithmetic
Geometric
Harmonic
Correct Answer :
C. Geometric
Related Questions
In Joule-Thomson porous plug experiment, the
Enthalpy does not remain constant
Entire apparatus is exposed to surroundings
Temperature remains constant
None of these
Any substance above its critical temperature exists as
Saturated vapour
Solid
Gas
Liquid
Out of the following refrigeration cycles, which one has the minimum COP (Co-efficient of performance)?
Air cycle
Carnot cycle
Ordinary vapour compression cycle
Vapour compression with a reversible expansion engine
Ideal gas law is applicable at
Low T, low P
High T, high P
Low T, high P
High T, low P
Throttling (Joule-Thomson effect) process is a constant __________ process.
Enthalpy
Entropy
Pressure
None of these
The chemical potential for a pure substance is __________ its partial molal free energy.
More than
Less than
Equal to
Not related to
In a working refrigerator, the value of COP is always
0
< 0
< 1
> 1
Adiabatic compression of a saturated water vapour makes it
Supersaturated
Superheated
Both (A) and (B)
Neither (A) nor (B)
The efficiency of an Otto engine compared to that of a diesel engine, for the same compression ratio will be
More
Less
Same
Data insufficient to predict
Which of the following is not a unit of the equilibrium constant Kp? (where, Δx = number of moles of products number of moles of reactants)
(atm)Δx, when Δx is negative
(atm)Δx, when Δx is positive
Dimensionless, when Δx = 0
(atm)Δx2, when Δx > 0
Change of heat content when one mole of compound is burnt in oxygen at constant pressure is called the
Calorific value
Heat of reaction
Heat of combustion
Heat of formation
Pick out the correct statement.
If an insoluble gas is passed through a volatile liquid placed in a perfectly insulated container, the temperature of the liquid will increase
A process is irreversible as long as Δ S for the system is greater than zero
The mechanical work done by a system is always equal to∫P.dV
The heat of formation of a compound is defined as the heat of reaction leading to the formation of the compound from its reactants
The acentric factor of a materical, 'ω', is defined as ω = -log10(Prsat)Tr-1 = 0.7, where, Prsat = reduced vapor pressure, Tr = reduced temperature. The value of acentric factor is always
> 2
< 1
> 1
< 3
After throttling, gas temperature
Decreases
Increases
Remain same
May increase or decrease; depends on the nature of the gas
Efficiency of a heat engine working on Carnot cycle between two temperature levels depends upon the
Two temperatures only
Pressure of working fluid
Mass of the working fluid
Mass and pressure both of the working fluid
Which of the following processes cannot be made reversible even under ideal condition of operation?
Free expansion of a gas
Compression of air in a compressor
Expansion of steam in a turbine
All (A), (B) & (C)
The effect of changing the evaporator temperature on COP as compared to that of changing the condenser temperature (in vapour compression refrigeration system) is
Less pronounced
More pronounced
Equal
Data insufficient, can't be predicted
Co-efficient of Performance (COP) of a refrigerator is the ratio of the
Work required to refrigeration obtained
Refrigeration obtained to the work required
Lower to higher temperature
Higher to lower temperature
The molar excess Gibbs free energy, gE, for a binary liquid mixture at T and P is given by, (gE/RT) = A . x1. x2, where A is a constant. The corresponding equation for ln y1, where y1 is the activity co-efficient of component 1, is
A . x22
Ax1
Ax2
Ax12
Which of the following is not an intensive property?
Molar heat capacity
Internal energy
Viscosity
None of these
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
In an isothermal process on an ideal gas, the pressure increases by 0.5 percent. The volume decreases by about __________ percent.
0.25
0.5
0.75
1
The value of gas constant 'R' is
1.987 cal/gm mole °K
1.987 BTU/lb. mole °R
Both (A) and (B)
Neither (A) nor (B)
__________ explains the equilibrium constant for any chemical reaction.
Henry's law
Law of mass action
Hess's law
None of these
Which of the following is not an extensive property?
Free energy
Entropy
Refractive index
None of these
Free energy
Decreases in all spontaneous (or irreversible) processes
Change during a spontaneous process has a negative value
Remains unchanged in reversible processes carried at constant temperature and pressure
All (A), (B) and (C)
Pick out the wrong statement.
Activity co-efficient is dimensionless.
In case of an ideal gas, the fugacity is equal to its pressure.
In a mixture of ideal gases, the fugacity of a component is equal to the partial pressure of the component.
The fugacity co-efficient is zero for an ideal gas
A refrigeration cycle is the same as a __________ cycle,
Turbine
Heat engine
Reversed heat engine
None of these
Which is a state function?
Specific volume
Work
Pressure
Temperature
All gases above its inversion temperature, in a throttling process will show
A heating effect
No change in temperature
A cooling effect
Either (A) or (C)