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What is the correct answer?

4

Solid and liquid phases of a substance are in equilibrium at the

A. Critical temperature

B. Melting point

C. Freezing point

D. Both (B) and (C)

Correct Answer :

D. Both (B) and (C)


Related Questions

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4

Pick out the wrong statement.

A. Enthalpies of all elements in their standard states are assumed to be zero

B. Combustion reactions are never endothermic in nature

C. Heat of reaction at constant volume is equal to the change in internal energy

D. Clausius-Clapeyron equation is not applicable to melting process

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4

Which is a state function?

A. Specific volume

B. Work

C. Pressure

D. Temperature

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4

A solute distributes itself between two nonmiscible solvents in contact with each other in such a way that, at a constant temperature, the ratio of its concentrations in two layers is constant, irrespective of its total amount. This is

A. The distribution law

B. Followed from Margules equation

C. A corollary of Henry's law

D. None of these

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4

The work done in isothermal compression compared to that in adiabatic compression will be

A. Less

B. More

C. Same

D. More or less depending upon the extent of work done

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4

In the decomposition of PCl5 represented by, PCl5 PCl3 + Cl2, decrease in the pressure of the system will __________ the degree of dissociation of PCl5.

A. Increase

B. Decrease

C. Not alter

D. None of these

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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

The number of degrees of freedom for an azeotropic mixture in a two component vapour-liquid equilibria is/are

A. Zero

B. One

C. Two

D. Three

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4

Gibbs phase rule finds application, when heat transfer occurs by

A. Conduction

B. Convection

C. Radiation

D. Condensation

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4

Pick out the correct statement.

A. Entropy and enthalpy are path functions

B. In a closed system, the energy can be exchanged with the surrounding, while matter cannot be exchanged

C. All the natural processes are reversible in nature

D. Work is a state function

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4

Trouton's ratio is given by (where λb, = molal heat of vaporisation of a substance at its normal boiling point, kcal/kmol Tb = normal boiling point, °K)

A. λb/Tb

B. Tb/λb

C. √(λb/Tb)

D. √(Tb/λb)

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4

The temperature at the eutectic point of the system is the __________ temperature that can be attained in the system.

A. Lowest

B. Highest

C. Average

D. None of these

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4

Pick out the wrong statement:

A. The expansion of a gas in vacuum is an irreversible process

B. An isometric process is a constant pressure process

C. Entropy change for a reversible adiabatic process is zero

D. Free energy change for a spontaneous process is negative

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4

Which of the following has the minimum value of COP for a given refrigeration effect?

A. Reverse Carnot cycle

B. Ordinary vapour-compression cycle

C. Vapour-compression process with a reversible expansion engine

D. Air refrigeration cycle

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4

The Maxwell relation derived from the differential expression for the Helmholtz free energy (dA) is

A. (∂T/∂V)S = - (∂P/∂S)V

B. (∂S/∂P)T = - (∂V/∂T)P

C. (∂V/∂S)P = (∂T/∂P)S

D. (∂S/∂V)T = (∂P/∂T)V

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4

For a constant volume process

A. dE = CpdT

B. dE = CvdT

C. dQ = dE + pdV

D. dW = pdV

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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

An irreversible process

A. Is the analog of linear frictionless motion in machines

B. Is an idealised visualisation of behaviour of a system

C. Yields the maximum amount of work

D. Yields an amount of work less than that of a reversible process

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4

The most important application of distribution law is in

A. Evaporation

B. Liquid extraction

C. Drying

D. Distillation

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4

Pick out the wrong statement.

A. The values of (∂P/∂V)T and (∂2P/∂V2)T are zero for a real gas at its critical point

B. Heat transferred is equal to the change in the enthalpy of the system, for a constant pressure, non-flow, mechanically reversible process

C. Thermal efficiency of a Carnot engine depends upon the properties of the working fluid besides the source & sink temperatures

D. During a reversible adiabatic process, the entropy of a substance remains constant

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4

What is the value of Joule-Thomson co-efficient for an ideal gas?

A. +ve

B. -ve

C. 0

D.

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4

Linde gas liquefaction process employs cooling

A. By throttling

B. By expansion in an engine

C. At constant pressure

D. None of these

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4

Which of the following identities can be most easily used to verify steam table data for superheated steam?

A. (∂T/∂V)S = (∂p/∂S)V

B. (∂T/∂P)S = (∂V/∂S)P

C. (∂P/∂T)V = (∂S/∂V)T

D. (∂V/∂T)P = -(∂S/∂P)T

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4

The principle applied in liquefaction of gases is

A. Adiabatic expansion

B. Joule-Thomson effect

C. Both (A) and (B)

D. Neither (A) nor (B)

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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

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

Pick out the wrong statement.

A. System (of partially miscible liquid pairs), in which the mutual solubility increases with rise in temperature, are said to possess an upper consolute temperature

B. Systems, in which the mutual solubility increases with decrease in temperature, are said to possess lower consolute temperature

C. Nicotine-water system shows both an upper as well as a lower consolute temperature, implying that they are partially miscible between these two limiting temperatures

D. None of these

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4

Which of the following liquid metals has the highest thermal conductivity?

A. Molten sodium

B. Molten lead

C. Mercury

D. Molten potassium

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4

A liquid under pressure greater than its vapour pressure for the temperature involved is called a __________ liquid.

A. Sub-cooled

B. Saturated

C. Non-solidifiable

D. None of these

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4

Free energy change of mixing two liquid substances is a function of the

A. Concentration of the constituents only

B. Quantities of the constituents only

C. Temperature only

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

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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)