At the absolute zero temperature, the entropy of every perfectly crystalline substance becomes zero. This follows from the
Third law of thermodynamics
Second law of thermodynamics
Nernst heat theorem
Maxwell's relations
Correct Answer :
A. Third law of thermodynamics
Related Questions
Pick out the correct statement.
A real gas on expansion in vacuum gets heated up
An ideal gas on expansion in vacuum gets cooled
An ideal gas on expansion in vacuum gets heated up
A real gas on expansion in vacuum cools down whereas ideal gas remains unaffected
The chemical potential of any constituent of an ideal solution depends on the __________ of the solution.
Temperature
Pressure
Composition
All (A), (B) and (C)
Compressibility factor-reduced pressure plot on reduced co-ordinates facilitates
Use of only one graph for all gases
Covering of wide range
Easier plotting
More accurate plotting
Entropy change for an irreversible process taking system and surrounding together is
0
> 0
< 0
None of these
Van Laar equation deals with the activity coefficients in
Binary solutions
Ternary solutions
Azeotropic mixture only
None of these
Free energy change of mixing two liquid substances is a function of the
Concentration of the constituents only
Quantities of the constituents only
Temperature only
All (A), (B) and (C)
The equation Tds = dE - PdV applies to
Single phase fluid of varying composition
Single phase fluid of constant composition
Open as well as closed systems
Both (B) and (C)
The thermodynamic law, PVy = constant, is not applicable in case of
Ideal compression of air
Free expansion of an ideal gas
Adiabatic expansion of steam in a turbine
Adiabatic compression of a perfect gas
The expression for entropy change given by, ΔS = - nR ln (P2/P1), holds good for
Expansion of a real gas
Reversible isothermal volume change
Heating of an ideal gas
Cooling of a real gas
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
To obtain integrated form of Clausius-Clapeyron equation, ln (P2/P1) = (ΔHV/R) (1/T1 - 1/T2) from the exact Clapeyron equation, it is assumed that the
Volume of the liquid phase is negligible compared to that of vapour phase
Vapour phase behaves as an ideal gas
Heat of vaporisation is independent of temperature
All (A), (B) & (C)
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
Choose the condition that must be specified in order to liquify CO2 (triple point for CO2 is - 57°C and 5.2 atm).
Pressure must be kept below 5.2 atm
Temperature must be kept above - 57°C
Pressure must be kept below 5.2 atm. and temperature must be kept above 57°C
Pressure and temperature must be kept below 5.2 atm. and - 57°C respectively
Pick out the wrong statement pertaining to the decomposition of PCl5 represented by, PCl5 PCl3 + Cl2.Degree of dissociation of PCl5 will
Decrease on addition of Cl2
Increase on addition of an inert gas at constant pressure
Decrease on increasing the pressure of the system
None of these
A gas performs the maximum work, when it expands
Non-uniformly
Adiabatically
Isobarically
Isothermally
For a stable phase at constant pressure and temperature, the fugacity of each component in a binary system __________ as its mole fraction increases.
Decreases
Increases
Remain same
Decreases linearly
During the phase transition, __________ changes.
Pressure
Volume
Temperature
All (A), (B) and (C)
As the temperature is lowered towards the absolute zero, the value of the quantity (∂ΔF/∂T) approaches
Zero
Unity
Infinity
None of these
If heat contents of CH4, C2H4 and C3H8 are -17.9, 12.5 and -24.8 kcal/mole respectively, than ΔH for the reaction CH4(g) + C2H4(g) C3H8(g) will be __________ Kcal.
-19.4
-30.2
55.2
-55.2
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.
Isometric
Polytropic
Isentropic
Isobaric
Cv for an ideal gas
Does not depend upon temperature
Is independent of pressure only
Is independent of volume only
Is independent of both pressure and volume
During a reversible isothermal expansion of an ideal gas, the entropy change is
+ve
0
-ve
∞
Molar heat capacity of water in equilibrium with ice at constant pressure is __________ Kcal/kg mole. °K
0
∞
50
100
Requisites of a reversible process is that the
System and surroundings pressure be equal
Friction in the system should be absent
System and surroundings temperature be equal
None of these
The number of degrees of freedom for an azeotropic mixture in a two component vapour-liquid equilibria is/are
Zero
One
Two
Three
(∂H/∂T)P is the mathematical expression for
CV
Entropy change
Gibbs free energy
None of these
In the reaction, C + O2 → CO2; ΔH = - 94 kcal. What is the heat content (enthalpy) of O2?
-94 kcal
> -94 kcal
< - 94 kcal
Zero
A cylinder contains 640 gm of liquid oxygen. The volume occupied (in litres) by the oxygen, when it is released and brought to standard conditions (0°C, 760 mm Hg) will be __________ litres.
448
224
22.4
Data insufficient; can't be computed
Joule-Thomson experiment is
Isobaric
Adiabatic
Isenthalpic
Both (B) & (C)
Those solutions in which there is no volume change upon mixing the components in the liquid state and which, when diluted do not undergo any heat change (i.e. heat of dilution is zero), are called __________ solutions.
Ideal
Real
Isotonic
None of these