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4

Lowering of condenser temperature (keeping the evaporator temperature constant) in case of vapour compression refrigeration system results in

A. Increased COP

B. Same COP

C. Decreased COP

D. Increased or decreased COP; depending upon the type of refrigerant

Correct Answer :

A. Increased COP


Related Questions

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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

Change of state namely evaporation condensation, freezing and melting is an __________ process.

A. Isothermal

B. Adiabatic

C. Isobaric

D. Isochoric

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4

In a turbine, the fluid expands almost

A. Isothermally

B. Isobarically

C. Adiabatically

D. None of these

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4

The value of Cp & Cv respectively for monatomic gases in Kcal/kg Mole.°K are

A. 5 & 3

B. 3.987 & 1.987

C. 1.987 & 0.66

D. 0.66 & 1.987

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4

The activity of an ideal gas is numerically __________ its pressure.

A. More than

B. Less than

C. Equal to

D. Data insufficient, can't be predicted

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4

The temperature at which a real gas obeys the ideal gas laws over a wide range of pressure is called __________ temperature.

A. Boyle

B. Inversion

C. Critical

D. Reduced

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4

The energy of activation of exothermic reaction is

A. Zero

B. Negative

C. Very large compared to that for endothermic reaction

D. Not possible to predict

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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

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4

The quantitative effect of temperature on chemical equilibrium is given by the

A. Vant-Hoff equation

B. Le-Chatelier's principle

C. Arrhenius equation

D. None of these

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4

What is the value of ln y (where y = activity co-efficient) for ideal gases?

A. Zero

B. Unity

C. Infinity

D. Negative

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4

For the reversible exothermic reaction, N2 + 3H2 2NH3, increase of pressure would

A. Shift the equilibrium towards right

B. Give higher yield of NH3

C. Both (B) and (C)

D. Neither (A) nor (B)

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4

The absolute entropy for all crystalline substances at absolute zero temperature is

A. Zero

B. Negative

C. More than zero

D. Indeterminate

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4

No work is done by the system, when a reaction occurs at constant

A. Volume

B. Temperature

C. Pressure

D. None of these

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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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4

Entropy change of the reaction, H2O (liquid) → H2O (gas), is termed as the enthalpy of

A. Solution

B. Vaporisation

C. Formation

D. Sublimation

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4

Critical temperature is defined as the temperature above which a gas will

A. Not liquify (barring exceptions)

B. Immediately liquify

C. Never liquify however high the pressure may be

D. None of these

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4

Pick out the wrong statement.

A. The net change in entropy in any reversible cycle is always zero

B. The entropy of the system as a whole in an irreversible process increases

C. The entropy of the universe tends to a maximum

D. The entropy of a substance does not remain constant during a reversible adiabatic change

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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

Co-efficient of Performance (COP) of a refrigerator is the ratio of the

A. Work required to refrigeration obtained

B. Refrigeration obtained to the work required

C. Lower to higher temperature

D. Higher to lower temperature

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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 efficiency of an Otto engine compared to that of a diesel engine, for the same compression ratio will be

A. More

B. Less

C. Same

D. Data insufficient to predict

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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 partial pressure of each constituent present in an alloy is __________ the total vapor pressure exerted by the alloy.

A. Less than

B. Equal to

C. More than

D. Either (B) or (C); depends on the type of alloy

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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

For an isothermal process, the internal energy of a gas

A. Increases

B. Decreases

C. Remains unchanged

D. Data insufficient, can't be predicted

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4

Throttling process is a/an __________ process.

A. Reversible and isothermal

B. Irreversible and constant enthalpy

C. Reversible and constant entropy

D. Reversible and constant enthalpy

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4

Standard temperature and pressure (S.T.P.) is

A. 0°C and 750 mm Hg

B. 15°C and 750 mm Hg

C. 0°C and 1 kgf/cm2

D. 15°C and 1 kgf/cm2

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4

Gibbs-Duhem equation

A. States that n11 + n22 + ....njj = 0, for a system of definite composition at constant temperature and pressure

B. Applies only to binary systems

C. Finds no application in gas-liquid equilibria involved in distillation

D. None of these

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4

Which of the following will increase the volume of a real gas by four times?

A. Doubling the absolute temperature as well as pressure of the gas

B. Reducing pressure to one fourth at constant temperature

C. Reducing temperature to one fourth at constant pressure

D. Reducing the temperature to half and doubling the pressure

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4

Chemical potential of ith component of a system is given by

A. μi = (∂F/∂ni)T, P, ni

B. μi = (∂A/∂ni)T, P, ni

C. μi = (∂F/∂ni)T, P

D. μi = (∂A/∂ni)T, P