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4

The main feature of Carnot refrigeration cycle is that, it

A. Does not need the addition of external work for its functioning

B. Transfers heat from high temperature to low temperature

C. Accomplishes the reverse effect of the heat engine

D. None of these

Correct Answer :

C. Accomplishes the reverse effect of the heat engine


Related Questions

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4

If we increase the pressure on a substance (which is at its triple point), then the triple point

A. Increases

B. Decreases

C. Remains unchanged

D. May increase or decrease; depends on the substance

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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

Air-refrigeration cycle

A. Is the most efficient of all refrigeration cycles

B. Has very low efficiency

C. Requires relatively large quantities of air to achieve a significant amount of refrigeration

D. Both (B) and (C)

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4

Which is not a refrigerant?

A. SO2

B. NH3

C. CCl2F2

D. C2H4Cl2

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4

Pick out the wrong statement.

A. Cp of monatomic gases such as metallic vapor is about 5 kcal/kg.atom

B. The heat capacity of solid inorganic substance is exactly equal to the heat capacity of the substance in the molten state

C. There is an increase in entropy, when a spontaneous change occurs in an isolated system

D. At absolute zero temperature, the heat capacity for many pure crystalline substances is zero

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4

Consider the reaction, C + O2 CO2; ΔH = - 94 kcal. What will be the value of ΔH for the reaction CO2 → C + O2?

A. -94 kcal

B. +94 kcal

C. > 94 kcal

D. < -94 kcal

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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

A Carnot cycle consists of the following steps:

A. Two isothermal and two isentropic

B. Two isobaric and two isothermal

C. Two isochoric and two isobaric

D. Two isothermals and two isochoric

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4

In any spontaneous process,

A. Only F decreases

B. Only A decreases

C. Both F and A decreases

D. Both F and A increase

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4

Specific/molar Gibbs free energy for a pure substance does not change during

A. Sublimation

B. Vaporisation

C. Melting

D. Either (A), (B) or (C)

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4

Gibbs free energy of a pure fluid approaches __________ as the pressure tends to zero at constant temperature.

A. Infinity

B. Minus infinity

C. Zero

D. None of these

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4

Pick out the wrong statement.

A. Surface tension of a substance vanishes at critical point, as there is no distinction between liquid and vapour phases at its critical point

B. Entropy of a system decreases with the evolution of heat

C. Change of internal energy is negative for exothermic reactions

D. The eccentric factor for all materials is always more than one

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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

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

The equation Tds = dE - PdV applies to

A. Single phase fluid of varying composition

B. Single phase fluid of constant composition

C. Open as well as closed systems

D. Both (B) and (C)

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4

In an irreversible process

A. Tds = dE - dW = 0

B. dE - dW - Tds = 0

C. Tds - dE + dW < 0

D. Tds - dT + dW < 0

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4

The Joule-Thomson co-efficient is defined as (∂T/∂P)H. Its value at the inversion point is

A.

B. 1

C. 0

D. -ve

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4

At __________ point, all the three phases (i.e. solid, liquid and gas) co-exist.

A. Eutectic

B. Triple

C. Plait

D. Critical

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4

The Carnot co-efficient of performance (COP) of a domestic air conditioner compared to a household refrigerator is

A. Less

B. More

C. Same

D. Dependent on climatic conditions

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4

__________ calorimeter is normally used for measuring the dryness fraction of steam, when it is very low.

A. Bucket

B. Throttling

C. Separating

D. A combination of separating & throttling

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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

The number of degrees of freedom at the triple point of water is

A. 0

B. 1

C. 2

D. 3

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4

Isotherm on an enthalpy-concentration diagram, for an ideal solution will be a

A. Straight line

B. Sine curve

C. Parabola

D. Hyperbola

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4

In an isothermal process on an ideal gas, the pressure increases by 0.5 percent. The volume decreases by about __________ percent.

A. 0.25

B. 0.5

C. 0.75

D. 1

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4

Dry ice is

A. Moisture free ice

B. Solid helium

C. Solid carbon dioxide

D. None of these

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4

The gas law (PV = RT) is true for an __________ change.

A. Isothermal

B. Adiabatic

C. Both (A) & (B)

D. Neither (A) nor (B)

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4

In the reaction, C + O2 → CO2; ΔH = - 94 kcal. What is the heat content (enthalpy) of O2?

A. -94 kcal

B. > -94 kcal

C. < - 94 kcal

D. Zero

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4

Gibbs free energy (F) is defined as

A. F = E - TS

B. F = H - TS

C. F = H + TS

D. F = E + TS

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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

The expression for entropy change given by, ΔS = nR ln (V2/V1) + nCv ln (T2/T1) is valid for

A. Reversible isothermal volume change

B. Heating of a substance

C. Cooling of a substance

D. Simultaneous heating and expansion of an ideal gas