The expression for entropy change, ΔS = n Cp . ln (T2/T1), is valid for the __________ of a substance.
Simultaneous pressure & temperature change
Heating
Cooling
Both (B) and (C)
Correct Answer :
D. Both (B) and (C)
Related Questions
Choose the condition that must be specified in order to liquify CO2 (triple point for CO2 is - 57°C and 5.2 atm).
Pressure must be kept below 5.2 atm
Temperature must be kept above - 57°C
Pressure must be kept below 5.2 atm. and temperature must be kept above 57°C
Pressure and temperature must be kept below 5.2 atm. and - 57°C respectively
Two substances are in equilibrium in a reversible chemical reaction. If the concentration of each substance is doubled, then the value of the equilibrium constant will be
Same
Doubled
Halved
One fourth of its original value
Which of the following is not correct for a reversible adiabatic process?
TVγ-1 = constant
p1-γ.TY = constant
PVγ = constant
None of these
Throttling (Joule-Thomson effect) process is a constant __________ process.
Enthalpy
Entropy
Pressure
None of these
Pick out the correct statement.
Like internal energy and enthalpy, the absolute value of standard entropy for elementary substances is zero
Melting of ice involves increase in enthalpy and a decrease in randomness
The internal energy of an ideal gas depends only on its pressure
Maximum work is done under reversible conditions
As the time is passing, entropy of the universe
Is increasing
Is decreasing
Remain constant
Data insufficient, can't be predicted
For the gaseous phase chemical reaction, C2H4(g) + H2O(g) ↔ C2H5OH(g), the equilibrium conversion does not depend on the
Steam to ethylene ratio
Temperature
Pressure
None of these
For a constant pressure reversible process, the enthalpy change (ΔH) of the system is
Cv.dT
Cp.dT
∫ Cp.dT
∫ Cv.dT
Pick out the correct statement.
The available energy in an isolated system for all irreversible (real) processes decreases
The efficiency of a Carnot engine increases, if the sink temperature is decreased
The reversible work for compression in non-flow process under isothermal condition is the change in Helmholtz free energy
All (A), (B) and (C)
Generation of heat by friction is an example of a/an __________ change.
Isothermal
Irreversible
Adiabatic
Reversible
Compound having large heat of formation is
More stable
Less stable
Not at all stable (like nascent O2)
Either more or less stable; depends on the compound
Joule-Thomson Co-efficient at any point on the inversion curve is
∞
+ve
0
-ve
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
Variation of equilibrium pressure with temperature for any two phases of a given substances is given by the __________ equation.
Gibbs-Duhem
Maxwell's
Clapeyron
None of these
Keeping the pressure constant, to double the volume of a given mass of an ideal gas at 27°C, the temperature should be raised to __________ °C.
270
327
300
540
Joule-Thomson effect i.e., a throttling process is a constant __________ process.
Entropy
Temperature
Internal energy
Enthalpy
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
One mole of nitrogen at 8 bar and 600 K is contained in a piston-cylinder arrangement. It is brought to 1 bar isothermally against a resisting pressure of 1 bar. The work done (in Joules) by the gas is
30554
10373
4988.4
4364.9
Refrigerants commonly used for domestic refrigerators are
Ethyl chloride or methyl chloride
Freon-12
Propane
NH3 or CO2
Thermal efficiency of a Carnot engine can approach 100%, only when the temperature of the
Cold reservoir approaches zero
Hot reservoir approaches infinity
Either (A) or (B)
Neither (A) nor (B)
Absolute zero temperature signifies the
Minimum temperature attainable
Temperature of the heat reservoir to which a Carnot engine rejects all the heat that is taken in
Temperature of the heat reservoir to which a Carnot engine rejects no heat
None of these
The equation relating E, P, V and T which is true for all substances under all conditions is given by (∂E/∂V)T = T(∂P/∂T)H - P. This equation is called the
Maxwell's equation
Thermodynamic equation of state
Equation of state
Redlich-Kwong equation of state
Which law of the thermodynamics provides basis for measuring the thermodynamic property?
First law
Zeroth law
Third law
Second law
For an ideal gas, the internal energy depends upon its __________ only.
Molecular size
Temperature
Volume
Pressure
Near their critical temperatures, all gases occupy volumes __________ that of the ideal gas.
Less than
Same as
More than
Half
Minimum number of phases that exists in a system is 1. Number of chemical species in a colloidal system is
1
2
3
4
Grams of butane (C4H10) formed by the liquefaction of 448 litres of the gas (measured at (STP) would be
580
640
1160
Data insufficient; can't be computed
Free energy changes for two reaction mechanism 'X' and 'Y are respectively - 15 and - 5 units. It implies that X is
Slower than Y
Faster than Y
Three times slower than Y
Three times faster than Y
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
Heat of reaction at constant volume is identified with __________ change.
Enthalpy
Internal energy
Either (A) or (B)
Neither (A) nor (B)