In an ideal solution, the activity of a component equals its
Mole fraction
Fugacity at the same temperature and pressure
Partial pressure
None of these
Correct Answer :
A. Mole fraction
Related Questions
Near their critical temperatures, all gases occupy volumes __________ that of the ideal gas.
Less than
Same as
More than
Half
Efficiency of a heat engine working on Carnot cycle between two temperature levels depends upon the
Two temperatures only
Pressure of working fluid
Mass of the working fluid
Mass and pressure both of the working fluid
A system is said to be at equilibrium, if the entropy of the system has reached __________ value.
Minimum
Zero
Maximum
None of these
When a gas in a vessel expands, its internal energy decreases. The process involved is
Reversible
Irreversible
Isothermal
Adiabatic
The first law of thermodynamics is a statement of conservation of
Heat
Momentum
Energy
Work
Pick out the wrong statement.
Minimum number of degree of freedom of a system is zero
Degree of freedom of a system containing a gaseous mixture of helium, carbon dioxide and hydrogen is 4
For a two phase system in equilibrium made up of four non-reacting chemical species, the number of degrees of freedom is 4
Enthalpy and internal energy change is zero during phase change processes like melting, vaporisation and sublimation
The free energy change for a chemical reaction is given by (where, K = equilibrium constant)
RT ln K
-RT ln K
-R ln K
T ln K
Throttling (Joule-Thomson effect) process is a constant __________ process.
Enthalpy
Entropy
Pressure
None of these
Law of corresponding states says that
Two different gases behave similarly, if their reduced properties (i.e. P, V and T) are same
The surface of separation (i. e. the meniscus) between liquid and vapour phase disappears at the critical temperature
No gas can be liquefied above the critical temperature, howsoever high the pressure may be.
The molar heat of energy of gas at constant volume should be nearly constant (about 3 calories)
Which of the following is not a unit of the equilibrium constant Kp? (where, Δx = number of moles of products number of moles of reactants)
(atm)Δx, when Δx is negative
(atm)Δx, when Δx is positive
Dimensionless, when Δx = 0
(atm)Δx2, when Δx > 0
For a constant volume process __________ by the system is used only to increase the internal energy.
Heat absorbed
Work done
Both (A) & (B)
Neither (A) nor (B)
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
Specific/molar Gibbs free energy for a pure substance does not change during
Sublimation
Vaporisation
Melting
Either (A), (B) or (C)
As the temperature is lowered towards the absolute zero, the value of ∂(ΔF)/∂T, then approaches
Unity
Zero
That of the heat of reaction
Infinity
When liquid and vapour phase of multi-component system are in equilibrium (at a given temperature and pressure), then chemical potential of each component is
Same in both the phases
Zero in both the phases
More in vapour phase
More in liquid phase
The melting point of paraffin wax (which contracts on solidification) __________ with pressure rise.
Increases
Decreases
Remains unchanged
Decreases linearly
Solid and liquid phases of a substance are in equilibrium at the
Critical temperature
Melting point
Freezing point
Both (B) and (C)
Pick out the correct statement.
The available energy in an isolated system for all irreversible (real) processes decreases
The efficiency of a Carnot engine increases, if the sink temperature is decreased
The reversible work for compression in non-flow process under isothermal condition is the change in Helmholtz free energy
All (A), (B) and (C)
A cyclic engine exchanges heat with two reservoirs maintained at 100 and 300°C respectively. The maximum work (in J) that can be obtained from 1000 J of heat extracted from the hot reservoir is
349
651
667
1000
Which of the following is affected by the temperature?
Fugacity
Activity co-efficient
Free energy
All (A), (B) & (C)
Degree of freedom of a system consisting of a gaseous mixture of H2 and NH3 will be
0
1
2
3
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)
Entropy change for an irreversible isolated system is
∞
0
< 0
> 0
The temperature at the eutectic point of the system is the __________ temperature that can be attained in the system.
Lowest
Highest
Average
None of these
The necessary and sufficient condition for equilibrium between two phases is
The concentration of each component should be same in the two phases
The temperature of each phase should be same
The pressure should be same in the two phases
The chemical potential of each component should be same in the two phases
Number of phases in a colloidal system is:
1
2
3
4
Which of the following behaves most closely like an ideal gas?
He
N2
O2
H2
Fugacity and pressure are numerically not equal for the gases
At low temperature and high pressure
At standard state
Both (A) and (B)
In ideal state
In a turbine, the fluid expands almost
Isothermally
Isobarically
Adiabatically
None of these
The amount of heat required to decompose a compound into its elements is __________ the heat of formation of that compound from its elements.
Less than
More than
Same as
Not related to