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4

Heat evolved/absorbed during conversion of a substance from one allotropic form to another is termed as the heat of

A. Fusion

B. Vaporisation

C. Transition

D. None of these

Correct Answer :

C. Transition


Related Questions

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4

A solid metallic block weighing 5 kg has an initial temperature of 500°C. 40 kg of water initially at 25°C is contained in a perfectly insulated tank. The metallic block is brought into contact with water. Both of them come to equilibrium. Specific heat of block material is 0.4 kJ.kg-1. K-1. Ignoring the effect of expansion and contraction and also the heat capacity to tank, the total entropy change in kJ.kg-1, K-1 is

A. -1.87

B. 0

C. 1.26

D. 3.91

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4

For organic compounds, group contribution method can be used for the estimation of

A. Critical properties

B. Specific gravity

C. Specific volume

D. Thermal conductivity

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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

Which of the following is a widely used refrigerant in vapour compression refrigeration system (using large centrifugal compressor)?

A. Freon

B. Liquid sulphur dioxide

C. Methyl chloride

D. Ammonia

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4

At a given temperature, the volume of a gas dissolved in a solvent __________ with increase in pressure.

A. Increases

B. Decreases

C. Remains unchanged

D. May increase or decrease; depends on the gas

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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

Extensive properties of a thermodynamic system depend upon the __________ of the system.

A. Specific volume

B. Temperature

C. Mass

D. Pressure

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4

In a reversible chemical reaction (where, Δx = number of moles of products-number of moles of reactants)

A. Addition of inert gas favours the forward reaction, when Δx is positive

B. Pressure has no effect on equilibrium, when Δn = 0

C. Addition of inert gas has no effect on the equilibrium constant at constant volume for any value of Δx (+ ve, - ve) or zero)

D. All 'a', 'b' & 'c'

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4

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

A. Unity

B. Zero

C. That of the heat of reaction

D. Infinity

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4

Entropy change of mixing two liquid substances depends upon the

A. Molar concentration

B. Quantity (i.e. number of moles)

C. Both (A) and (B)

D. Neither (A) nor (B)

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4

Fugacity is a measure of the

A. Escaping tendencies of the same substance in different phases of a system

B. Relative volatility of a mixture of two miscible liquids

C. Behaviour of ideal gases

D. None of these

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4

The reaction A (l) → R(g) is allowed to reach equilibrium conditions in an autoclave. At equilibrium, there are two phases, one a pure liquid phase of A and the other a vapor phase of A, R and S. Initially A alone is present. The numbers of degrees of freedom are:

A. 1

B. 2

C. 3

D. 0

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4

Pick out the wrong statement.

A. Activity co-efficient is dimensionless.

B. In case of an ideal gas, the fugacity is equal to its pressure.

C. In a mixture of ideal gases, the fugacity of a component is equal to the partial pressure of the component.

D. The fugacity co-efficient is zero for an ideal gas

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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

Melting of wax is accompanied with __________ in entropy.

A. Increase

B. Decrease

C. No change

D. None of these

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4

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

Compressibility factor (i.e., the ratio of actual volume of gas to the volume predicted by ideal gas law) for all gases are

A. Always greater than one

B. Same at the same reduced temperature

C. Same at the same reduced pressure

D. Both (B) & (C)

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4

Joule-Thomson Co-efficient at any point on the inversion curve is

A.

B. +ve

C. 0

D. -ve

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4

For multi-component multiple phases to be in equilibrium at the same pressure and temperature, the __________ of each component must be same in all phases.

A. Chemical potential

B. Fugacity

C. Both (A) and (B)

D. Neither (A) nor (B)

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4

The internal energy of a gas obeying P (V - b) RT (where, b is a positive constant and has a constant Cv), depends upon its

A. Pressure

B. Volume

C. Temperature

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

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4

Isobaric process means a constant process.

A. Temperature

B. Pressure

C. Volume

D. Entropy

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4

The specific heat of saturated water vapour at 100°C is

A.

B. -ve

C. 0

D. +ve

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4

While dissolving a gas into a liquid at a constant temperature, the ratio of the concentration of the gas in the solution phase and in the gaseous phase is

A. Infinity

B. Unity

C. Constant

D. Negative

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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

Gibbs free energy at constant pressure and temperature under equilibrium conditions is

A.

B. 0

C. Maximum

D. Minimum

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4

Which of the following has the least thermal efficiency?

A. Steam engine

B. Carnot engine

C. Diesel engine

D. Otto engine

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4

Critical solution temperature (or the consolute temperature) for partially miscible liquids (e.g., phenol-water) is the minimum temperature at which

A. A homogeneous solution (say of phenol water) is formed

B. Mutual solubility of the two liquids shows a decreasing trend

C. Two liquids are completely separated into two layers

D. None of these

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4

Refrigerants commonly used for domestic refrigerators are

A. Ethyl chloride or methyl chloride

B. Freon-12

C. Propane

D. NH3 or CO2

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4

Thermal efficiency of a Carnot engine can approach 100%, only when the temperature of the

A. Cold reservoir approaches zero

B. Hot reservoir approaches infinity

C. Either (A) or (B)

D. Neither (A) nor (B)

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4

In the equation, PVn = constant, if the value of n is in between 1 and y (i.e. Cp/Cv), then it represents a reversible __________ process.

A. Isometric

B. Polytropic

C. Isentropic

D. Isobaric