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4

High pressure steam is expanded adiabatically and reversibly through a well insulated turbine, which produces some shaft work. If the enthalpy change and entropy change across the turbine are represented by ΔH and ΔS respectively for this process:

A. Δ H = 0 and ΔS = 0

B. Δ H ≠ 0 and ΔS = 0

C. Δ H ≠ 0 and ΔS ≠ 0

D. Δ H = 0 and ΔS ≠ 0

Correct Answer :

B. Δ H ≠ 0 and ΔS = 0


Related Questions

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4

In polytropic process (PVn = constant), if n = 1; it means a/an __________ process.

A. Adiabatic

B. Reversible

C. Isothermal

D. None of these

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4

Adiabatic compression of a saturated water vapour makes it

A. Supersaturated

B. Superheated

C. Both (A) and (B)

D. Neither (A) nor (B)

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4

The chemical potential of a component (μi) of a phase is the amount by which its capacity for doing all work, barring work of expansion is increased per unit amount of substance added for an infinitesimal addition at constant temperature and pressure. It is given by

A. (∂E/∂ni)S, v, nj

B. (∂G/∂ni)T, P, nj = (∂A/∂ni) T, v, nj

C. (∂H/∂ni)S, P, nj

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

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4

Fundamental principle of refrigeration is based on the __________ law of thermodynamics.

A. Zeroth

B. First

C. Second

D. Third

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4

Work done in case of free expansion is

A. Indeterminate

B. Zero

C. Negative

D. None of these

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4

Which of the following is not an extensive property?

A. Free energy

B. Entropy

C. Refractive index

D. None of these

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4

Water on heating from 1 to 4°C

A. Contracts

B. Expands

C. Has same volume

D. May contract or expand

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4

Which law of the thermodynamics provides basis for measuring the thermodynamic property?

A. First law

B. Zeroth law

C. Third law

D. Second law

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4

Specific __________ does not change during a phase change (e.g. sublimation, melting, vaporisation etc.).

A. Entropy

B. Internal energy

C. Enthalpy

D. Gibbs free energy

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4

When pressure is applied on the system, ice ↔ water, then

A. Equilibrium cannot be established

B. More ice will be formed

C. More water will be formed

D. Evaporation of water will take place

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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

Equilibrium constant of a reaction varies with the

A. Initial concentration of the reactant

B. Pressure

C. Temperature

D. None of these

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4

Heat pump

A. Accomplishes only space heating in winter

B. Accomplishes only space cooling in summer

C. Accomplishes both (A) and (B)

D. Works on Carnot cycle

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4

With increase in compression ratio, the efficiency of the otto engine

A. Increases

B. Decreases

C. Remain constant

D. Increases linearly

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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

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

A. Same

B. Doubled

C. Halved

D. One fourth of its original value

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4

A/an __________ system is exemplified by a vessel containing a volatile liquid in contact with its vapor.

A. Isolated

B. Closed

C. Open

D. None of these

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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

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

__________ does not change during phase transformation processes like sublimation, melting & vaporisation.

A. Entropy

B. Gibbs free energy

C. Internal energy

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

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4

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.

A. Decreases

B. Increases

C. Remains constant

D. Decreases logarithmically

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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

The expression for entropy change given by, ΔS = - nR ln (P2/P1), holds good for

A. Expansion of a real gas

B. Reversible isothermal volume change

C. Heating of an ideal gas

D. Cooling of a real gas

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4

Out of the following refrigeration cycles, which one has the minimum COP (Co-efficient of performance)?

A. Air cycle

B. Carnot cycle

C. Ordinary vapour compression cycle

D. Vapour compression with a reversible expansion engine

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4

Enthalpy of a gas depends upon its

A. Temperature

B. Mass

C. Volume

D. Pressure

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4

Degree of freedom of a system consisting of a gaseous mixture of H2 and NH3 will be

A. 0

B. 1

C. 2

D. 3

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4

(∂H/∂T)P is the mathematical expression for

A. CV

B. Entropy change

C. Gibbs free energy

D. None of these

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4

Which of the following is not a common refrigerant?

A. Freon-12

B. Ethylene

C. Ammonia

D. Carbon dioxide

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4

Change of heat content when one mole of compound is burnt in oxygen at constant pressure is called the

A. Calorific value

B. Heat of reaction

C. Heat of combustion

D. Heat of formation

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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