A solid is transformed into vapour without going to the liquid phase at
Triple point
Boiling point
Below triple point
Always
Correct Answer :
A. Triple point
Related Questions
Pick out the correct statement.
Entropy and enthalpy are path functions
In a closed system, the energy can be exchanged with the surrounding, while matter cannot be exchanged
All the natural processes are reversible in nature
Work is a state function
Internal energy change of a system over one complete cycle in a cyclic process is
Zero
+ve
-ve
Dependent on the path
Chemical engineering thermodynamics is concerned with the __________ in/of chemical processes.
Reaction mechanism
Calculation of rates
Energy transformation from one form to another
None of these
When a gas is expanded from high pressure region to low pressure region; temperature change occurs. This phenomenon is related to the
Gibbs-Duhem equation
Gibbs-Helmholtz equation
Third law of thermodynamics
Joule-Thomson effect
Joule-Thomson co-efficient for a perfect gas is
Zero
Positive
Negative
None of these
As the temperature is lowered towards the absolute zero, the value of the quantity (∂ΔF/∂T) approaches
Zero
Unity
Infinity
None of these
For a cyclic process, a fixed ratio between heat and work
Always exists
May exist
Never exists
Is difficult to predict
A gas performs the maximum work, when it expands
Non-uniformly
Adiabatically
Isobarically
Isothermally
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
Pick out the correct equation relating 'F' and 'A'.
F = A + PV
F = E + A
F = A - TS
F = A + TS
Internal energy of an ideal gas
Increases with increase in pressure
Decreases with increase in temperature
Is independent of temperature
None of these
The change in Gibbs free energy for vaporisation of a pure substance is
Positive
Negative
Zero
May be positive or negative
Which of the following exemplifies an adiabatic process?
Melting of ice
Condensation of alcohol vapor
Sudden bursting of a cycle tube
Evaporation of water
During a reversible isothermal expansion of an ideal gas, the entropy change is
+ve
0
-ve
∞
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
A chemical reaction will occur spontaneously at constant pressure and temperature, if the free energy is
Zero
Positive
Negative
None of these
After throttling, gas temperature
Decreases
Increases
Remain same
May increase or decrease; depends on the nature of the gas
At __________ point, all the three phases (i.e. solid, liquid and gas) co-exist.
Eutectic
Triple
Plait
Critical
Gibbs free energy of mixing at constant pressure and temperature is always
0
∞
+ ve
- ve
In a working refrigerator, the value of COP is always
0
< 0
< 1
> 1
Adiabatic compression of a saturated water vapour makes it
Supersaturated
Superheated
Both (A) and (B)
Neither (A) nor (B)
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
Which of the following is Virial equation of state?
(p + a/V2)(V - b) = nRT
PV = nRT
PV = A + B/V + C/V2 + D/V3 + ...
None of these
If different processes are used to bring about the same chemical reaction, the enthalpy change is same for all of them. This is __________ law.
Hess's
Kirchoff's
Lavoisier and Laplace
None of these
Which of the following decreases with increase in pressure?
Melting point of ice
Melting point of wax
Boiling point of liquids
None of these
In a turbine, the fluid expands almost
Isothermally
Isobarically
Adiabatically
None of these
The most important application of distribution law is in
Evaporation
Liquid extraction
Drying
Distillation
A system is said to be isopiestic, if there is no __________ change.
Temperature
Pressure
Volume
None of these
In an ideal refrigeration cycle, the change in internal energy of the fluid is
+ve
-ve
0
Either of the above three; depends on the nature of refrigerant
With increase in reduced temperature, the fugacity co-efficient of a gas at constant reduced pressure
Increases
Decreases
Remain same
Decreases linearly