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4

Enthalpy changes over a constant pressure path are always zero for __________ gas.

A. Any

B. A perfect

C. An easily liquefiable

D. A real

Correct Answer :

B. A perfect


Related Questions

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4

For an ideal gas, the enthalpy

A. Increases with rise in pressure

B. Decreases with rise in pressure

C. Is independent of pressure

D. Is a path function

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4

The kinetic energy of gas molecule is zero at

A. 0°C

B. 273°C

C. 100°C

D. -273°C

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4

Which of the following is not a reversible process?

A. Expansion of an ideal gas against constant pressure

B. Atmospheric pressure vaporisation of water at 100°C

C. Solution of NaCl in water at 50°C

D. None of these

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4

For the gaseous phase chemical reaction, C2H4(g) + H2O(g) ↔ C2H5OH(g), the equilibrium conversion does not depend on the

A. Steam to ethylene ratio

B. Temperature

C. Pressure

D. None of these

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4

Pick out the wrong statement.

A. A refrigeration cycle violates the second law of thermodynamics

B. Refrigeration cycle is normally represented by a temperature vs. entropy plot

C. In a refrigerator, work required decreases as the temperature of the refrigerator and the temperature at which heat is rejected increases

D. One ton of refrigeration is equivalent to the rate of heat absorption equal to 3.53 kW

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4

All gases during throttling process at atmospheric temperature and pressure show a cooling effect except

A. CO2

B. H2

C. O2

D. N2

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4

Mollier diagram is a plot of

A. Temperature vs. enthalpy

B. Temperature vs. enthalpy

C. Entropy vs. enthalpy

D. Temperature vs. internal energy

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4

A solid is transformed into vapour without going to the liquid phase at

A. Triple point

B. Boiling point

C. Below triple point

D. Always

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4

Third law of thermodynamics is helpful in

A. Prediction of the extent of a chemical reaction

B. Calculating absolute entropies of substances at different temperature

C. Evaluating entropy changes of chemical reaction

D. Both (B) and (C)

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4

Specific __________ does not change during phase change at constant temperature and pressure.

A. Entropy

B. Gibbs energy

C. Internal energy

D. Enthalpy

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4

In a working refrigerator, the value of COP is always

A. 0

B. < 0

C. < 1

D. > 1

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4

After throttling, gas temperature

A. Decreases

B. Increases

C. Remain same

D. May increase or decrease; depends on the nature of the gas

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4

The specific heat of saturated water vapour at 100°C is

A.

B. -ve

C. 0

D. +ve

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4

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

A. 30554

B. 10373

C. 4988.4

D. 4364.9

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4

Mollier chart is a __________ plot.

A. Pressure vs. enthalpy

B. Pressure vs. volume

C. Enthalpy vs. entropy

D. Temperature vs. entropy

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4

When a system is in equilibrium for all possible processes, the differential or finite change of entropy is

A. < 0

B. > 0

C. = 0

D. None of these

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4

Gibbs-Duhem equation relates composition in liquid phase and the __________ at constant temperature & pressure.

A. Fugacity

B. Partial pressure

C. Activity co-efficient

D. All (A), (B), and (C)

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4

Refrigeration cycle

A. Violates second law of thermodynamics

B. Involves transfer of heat from low temperature to high temperature

C. Both (A) and (B)

D. Neither (A) nor (B)

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4

When liquid and vapour phase of multi-component system are in equilibrium (at a given temperature and pressure), then chemical potential of each component is

A. Same in both the phases

B. Zero in both the phases

C. More in vapour phase

D. More in liquid phase

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4

A chemical reaction will occur spontaneously at constant pressure and temperature, if the free energy is

A. Zero

B. Positive

C. Negative

D. None of these

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4

Which of the following equations is used for the prediction of activity co-efficient from experiments?

A. Van Laar equation

B. Margules equation

C. Wilson's equation

D. All (A), (B) and (C)

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4

The root mean square speed of molecules of a gas is equal to (where, m = mass of the molecule K = Boltzmanns constant, T = absolute temperature)

A. √(2KT/m)

B. √(3KT/m)

C. √(6KT/m)

D. 3KT/m

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4

Tea kept in a thermos flask is vigorously shaken. If the tea is considered as a system, then its temperature will

A. Increase

B. Decrease

C. Remain unchanged

D. First fall and then rise

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4

__________ explains the equilibrium constant for any chemical reaction.

A. Henry's law

B. Law of mass action

C. Hess's law

D. None of these

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4

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

A. Maxwell's equation

B. Thermodynamic equation of state

C. Equation of state

D. Redlich-Kwong equation of state

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4

Isobaric process means a constant process.

A. Temperature

B. Pressure

C. Volume

D. Entropy

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4

4 kg moles of an ideal gas expands in vacuum spontaneously. The work done is

A. 4 J

B.

C. 0

D. 8 J

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4

Pick out the correct statement.

A. A real gas on expansion in vacuum gets heated up

B. An ideal gas on expansion in vacuum gets cooled

C. An ideal gas on expansion in vacuum gets heated up

D. A real gas on expansion in vacuum cools down whereas ideal gas remains unaffected

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4

Entropy of the system decreases, when

A. Snow melts into water

B. A gas expands spontaneously from high pressure to low pressure

C. Water is converted into ice

D. Both (B) & (C)

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4

A refrigeration cycle is a reversed heat engine. Which of the following has the maximum value of the co-efficient of performance (COP) for a given refrigeration effect?

A. Vapor compression cycle using expansion valve

B. Air refrigeration cycle

C. Vapor compression cycle using expansion engine

D. Carnot refrigeration cycle