Heat evolved/absorbed during conversion of a substance from one allotropic form to another is termed as the heat of
Fusion
Vaporisation
Transition
None of these
Correct Answer :
C. Transition
Related Questions
Minimum number of phases that exists in a system is 1. Number of chemical species in a colloidal system is
1
2
3
4
Gibbs free energy (G) is represented by, G = H - TS, whereas Helmholtz free energy, (A) is given by, A = E - TS. Which of the following is the Gibbs-Helmholtz equation?
[∂(G/T)/∂T] = - (H/T2)
[∂(A/T)/∂T]V = - E/T2
Both (A) and (B)
Neither (A) nor (B)
Which of the following diagrams does not represent an Otto cycle?
None of these
Out of the following refrigeration cycles, which one has maximum COP?
Air cycle
Carnot cycle
Ordinary vapor compression cycle
Vapor compression with a reversible expansion engine
Cp of a gas at its critical temperature and pressure
Becomes zero
Becomes infinity
Equals 1 kcal/kmol °K
Equals 0.24 kcal/kmol °K
Gibbs-Duhem equation relates composition in liquid phase and the __________ at constant temperature & pressure.
Fugacity
Partial pressure
Activity co-efficient
All (A), (B), and (C)
Claude gas liquefaction process employs cooling
At constant pressure
By throttling
By expansion in an engine
None of these
For a real gas, the chemical potential is given by
RT d ln P
RT d ln f
R d ln f
None of these
At 60° C, vapour pressure of methanol and water are 84.562 kPa and 19.953 kPa respectively. An aqueous solution of methanol at 60° C exerts a pressure of 39.223 kPa; the liquid phase and vapour phase mole fractions of methanol are 0.1686 and 0.5714 respectively. Activity co-efficient of methanol is
1.572
1.9398
3.389
4.238
__________ explains the equilibrium constant for any chemical reaction.
Henry's law
Law of mass action
Hess's law
None of these
The activity of an ideal gas is numerically __________ its pressure.
More than
Less than
Equal to
Data insufficient, can't be predicted
A gas has a volume of 27.3 c.c. at 0°C. Its volume at 10°C (if pressure remains unchanged) will be __________ c.c.
2.73
28.3
273
283
If the heat of solution of an ideal gas in a liquid is negative, then its solubility at a given partial pressure varies with the temperature as
Solubility increases as temperature increases
Solubility increases as temperature decreases
Solubility is independent of temperature
Solubility increases or decreases with temperature depending on the Gibbs free energy change of solution
The third law of thermodynamics states that the
Heat capacity of a crystalline solid is zero at absolute zero temperature
Heat transfer from low temperature to high temperature source is not possible without external work
Gases having same reduced properties behaves similarly
None of these
Lowering of condenser temperature (keeping the evaporator temperature constant) in case of vapour compression refrigeration system results in
Increased COP
Same COP
Decreased COP
Increased or decreased COP; depending upon the type of refrigerant
Throttling (Joule-Thomson effect) process is a constant __________ process.
Enthalpy
Entropy
Pressure
None of these
The partial molar enthalpy of a component in an ideal binary gas mixture of composition Z, at a temperature T and pressure P, is a function only of
T
T and P
T, P and Z
T and Z
Entropy is a measure of the __________ of a system.
Disorder
Orderly behaviour
Temperature changes only
None of these
The quantitative effect of temperature on chemical equilibrium is given by the
Vant-Hoff equation
Le-Chatelier's principle
Arrhenius equation
None of these
Out of the following refrigeration cycles, which one has the minimum COP (Co-efficient of performance)?
Air cycle
Carnot cycle
Ordinary vapour compression cycle
Vapour compression with a reversible expansion engine
The first law of thermodynamics is a restatement of the law of conservation of
Mass
Energy
Momentum
None of these
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
100,000 kW
160,000 kW
200,000 kW
320,000 kW
For an irreversible process involving only pressure-volume work
(dF)T, p <0
(dF)T, p = 0
(dF)T, p > 0
(dA)T, v >0
Trouton's ratio of __________ liquids is calculated using Kistyakowsky equation.
Polar
Non-polar
Both (A) & (B)
Neither (A) nor (B)
Co-efficient of Performance (COP) of a refrigerator is the ratio of the
Work required to refrigeration obtained
Refrigeration obtained to the work required
Lower to higher temperature
Higher to lower temperature
The chemical potential for a pure substance is __________ its partial molal free energy.
More than
Less than
Equal to
Not related to
Linde gas liquefaction process employs cooling
By throttling
By expansion in an engine
At constant pressure
None of these
The temperature at which both liquid and gas phases are identical, is called the __________ point.
Critical
Triple
Freezing
Boiling
Pick out the wrong statement.
At constant pressure, solubility of a gas in a liquid diminishes with rise in temperature
Normally, the gases which are easily liquefied are more soluble in common solvents
The gases which are capable of forming ions in aqueous solution are much more soluble in water than in other solvents
At constant pressure, solubility of a gas in a liquid increases with rise in temperature
In case of a close thermodynamic system, there is __________ across the boundaries.
No heat and mass transfer
No mass transfer but heat transfer
Mass and energy transfer
None of these