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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

Correct Answer :

D. Air refrigeration cycle


Related Questions

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When a gas in a vessel expands, its internal energy decreases. The process involved is

A. Reversible

B. Irreversible

C. Isothermal

D. Adiabatic

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A domestic refrigerator has a/an __________ cooled condenser.

A. Water

B. Air

C. Evaporative

D. Gas

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As pressure approaches zero, the ratio of fugacity to pressure (f/P) for a gas approaches

A. Zero

B. Unity

C. Infinity

D. An indeterminate value

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4

Which of the following is not an equation of state?

A. Bertholet equation

B. Clausius-Clapeyron equation

C. Beattie-Bridgeman equation

D. None of these

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In case of a reversible process (following pvn = constant), work obtained for trebling the volume (v1 = 1 m3 and v23 m3) is maximum, when the value of 'n' is

A. 0

B. 1

C. y = 1.44

D. 1.66

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4

Forward reaction will be favoured for the exothermic reaction, represented by CO + H2O CO2 + H2, by

A. Low temperature and high pressure

B. Low temperature and low pressure

C. High temperature and high pressure

D. High temperature and low pressure

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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

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The unit of equilibrium constant of a chemical reaction is the same as that of

A. Molar concentration

B. Temperature

C. Internal energy

D. None of these

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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

The following heat engine produces power of 100,000 kW. The heat engine operates between 800 K and 300 K. It has a thermal efficiency equal to 50% of that of the Carnot engine for the same temperature. The rate at which heat is absorbed from the hot reservoir is

A. 100,000 kW

B. 160,000 kW

C. 200,000 kW

D. 320,000 kW

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During Joule-Thomson expansion of gases

A. Enthalpy remains constant

B. Entropy remains constant

C. Temperature remains constant

D. None of these

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4

Pressure-enthalpy chart is useful in refrigeration. The change in internal energy of an ideal fluid used in ideal refrigeration cycle is

A. Positive

B. Negative

C. Zero

D. Infinity

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Cp - Cv = R is valid for __________ gases.

A. Ideal

B. Very high pressure

C. Very low temperature

D. All of the above

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Cv for an ideal gas

A. Does not depend upon temperature

B. Is independent of pressure only

C. Is independent of volume only

D. Is independent of both pressure and volume

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Reduced pressure of a gas is the ratio of its

A. Pressure to critical pressure

B. Critical pressure to pressure

C. Pressure to pseudocritical pressure

D. Pseudocritical pressure to pressure

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The adiabatic throttling process of a perfect gas is one of constant enthalpy

A. In which there is a temperature drop

B. Which is exemplified by a non-steady flow expansion

C. Which can be performed in a pipe with a constriction

D. In which there is an increase in temperature

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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

For an ideal solution, the value of activity co-efficient is

A. 0

B. 1

C. < 1

D. > 1

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Entropy change for an irreversible process taking system and surrounding together is

A. 0

B. > 0

C. < 0

D. None of these

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When a system in equilibrium is subjected to a change in temperature, pressure or concentration, the equilibrium is displaced in a direction which tends to undo the effect of the change. This is called the

A. Le-Chatelier principle

B. Kopp's rule

C. Law of corresponding state

D. Arrhenius hypothesis

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Joule-Thomson effect i.e., a throttling process is a constant __________ process.

A. Entropy

B. Temperature

C. Internal energy

D. Enthalpy

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The most important application of distribution law is in

A. Evaporation

B. Liquid extraction

C. Drying

D. Distillation

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The effect of changing the evaporator temperature on COP as compared to that of changing the condenser temperature (in vapour compression refrigeration system) is

A. Less pronounced

B. More pronounced

C. Equal

D. Data insufficient, can't be predicted

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4

For a single component two phase mixture, the number of independent variable properties are

A. Two

B. One

C. Zero

D. Three

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The difference between isothermal compressibility and adiabatic compressibility for an ideal gas is

A. 0

B. +ve

C. -ve

D.

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Filling of gas from a high pressure cylinder into small bottles is an example of a/an __________ process.

A. Equilibrium

B. Adiabatic

C. Steady

D. Unsteady

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When liquid and vapour phases of one component system are in equilibrium (at a given temperature and pressure), the molar free energy is

A. More in vapour phase

B. More in liquid phase

C. Same in both the phases

D. Replaced by chemical potential which is more in vapour phase

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For an ideal gas, the internal energy depends upon its __________ only.

A. Molecular size

B. Temperature

C. Volume

D. Pressure

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__________ functions are exemplified by heat and work.

A. Path

B. Point

C. State

D. None of these

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In case of a close thermodynamic system, there is __________ across the boundaries.

A. No heat and mass transfer

B. No mass transfer but heat transfer

C. Mass and energy transfer

D. None of these