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4

If different processes are used to bring about the same chemical reaction, the enthalpy change is same for all of them. This is __________ law.

A. Hess's

B. Kirchoff's

C. Lavoisier and Laplace

D. None of these

Correct Answer :

A. Hess's


Related Questions

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4

A system is said to be isopiestic, if there is no __________ change.

A. Temperature

B. Pressure

C. Volume

D. None of these

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4

PVγ = Constant (where, γ = Cp/Cv) is valid for a/an __________ process.

A. Isothermal

B. Isentropic

C. Isobaric

D. Adiabatic

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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

Gibbs-Helmholtz equation is

A. ΔF = ΔH + T [∂(ΔF)/∂T]P

B. ΔF = ΔH - TΔT

C. d(E - TS) T, V < 0

D. dP/dT = ΔHvap/T.ΔVvap

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4

The necessary and sufficient condition for equilibrium between two phases is

A. The concentration of each component should be same in the two phases

B. The temperature of each phase should be same

C. The pressure should be same in the two phases

D. The chemical potential of each component should be same in the two phases

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4

High __________ is an undesirable property for a good refrigerant.

A. Specific heat

B. Latent heat of vaporisation

C. Viscosity

D. Specific vapor volume

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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

Air enters an adiabatic compressor at 300K. The exit temperature for a compression ratio of 3, assuming air to be an ideal gas (Y = Cp/Cv = 7/5) and the process to be reversible, is

A. 300 × (32/7)

B. 300 × (33/5)

C. 300 × (333/7)

D. 300 × (35/7)

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4

On opening the door of an operating refrigerator kept in a closed room, the temperature of the room will

A. Increase

B. Decrease

C. Remain same

D. Increase in summer and will decrease in winter

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4

Cv is given by

A. (∂E/∂T)V

B. (∂E/∂V)T

C. (∂E/∂P)V

D. (∂V/∂T)P

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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 the __________ temperature.

A. Critical

B. Boyle

C. Inversion

D. Reduced

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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

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

At the critical point of a substance

A. The surface tension vanishes

B. Liquid and vapour have the same density

C. There is no distinction between liquid and vapour phases

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

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4

In the equation, PVn = constant, if the value of n = 1, then it represents a reversible __________ process.

A. Isothermal

B. Isobaric

C. Polytropic

D. Adiabatic

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4

Enthalpy changes over a constant pressure path are always zero for __________ gas.

A. Any

B. A perfect

C. An easily liquefiable

D. A real

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4

Mollier diagram is a plot of

A. Temperature vs. enthalpy

B. Temperature vs. enthalpy

C. Entropy vs. enthalpy

D. Temperature vs. internal energy

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4

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

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4

Number of components (C), phase (P) and degrees of freedom (F) are related by Gibbs phase rule as

A. P + F - C = 2

B. C = P - F + 2

C. F = C - P - 2

D. P = F - C - 2

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4

Absolute zero temperature signifies the

A. Minimum temperature attainable

B. Temperature of the heat reservoir to which a Carnot engine rejects all the heat that is taken in

C. Temperature of the heat reservoir to which a Carnot engine rejects no heat

D. None of these

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4

The expression, ΔG = nRT. ln(P2/P1), gives the free energy change

A. With pressure changes at constant temperature

B. Under reversible isothermal volume change

C. During heating of an ideal gas

D. During cooling of an ideal gas

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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

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4

In a homogeneous solution, the fugacity of a component depends upon the

A. Pressure

B. Composition

C. Temperature

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

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4

The internal energy of an incompressible fluid depends upon its

A. Pressure

B. Temperature

C. Both (A) & (B)

D. Neither (A) nor (B)

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4

COP of a refrigerator drawing 1 kW of power per ton of refrigeration is about

A. 0.5

B. 3.5

C. 4.5

D. 8.5

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4

As the temperature is lowered towards the absolute zero, the value of the quantity (∂ΔF/∂T) approaches

A. Zero

B. Unity

C. Infinity

D. None of these

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4

In the reaction, represented by, 2SO2 + O2 2SO3; ΔH = - 42 kcal; the forward reaction will be favoured by

A. Low temperature

B. High pressure

C. Both (A) and (B)

D. Neither (A) nor (B)

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4

Isobaric process means a constant process.

A. Temperature

B. Pressure

C. Volume

D. Entropy

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4

For a thermodynamic system containing 'x' chemical species, the maximum number of phases that can co-exist at equilibrium is

A. x

B. x + 1

C. x + 2

D. x + 3

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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