PPSC Chemistry Lecturer Preparation (Test # 06)- Malik Xufyan 03137355727

1. Malik Xufyan WhatsApp # 0313-7355727
1 | P a g e
PPSC CHEMISTRY CLASS
Test Session
CH: Thermodynamics
Test # 06
For more WhatsApp # 0313-7355727
Topics:
1. Standard Free Energy
2. Chemical Equilibrium
3. Concept of Residual Entropy
Standard Free Energy
1. Which statement is incorrect?
a) At constant pressure, ΔH = ΔE + PΔV
b) The thermodynamic symbol for entropy is S.
c) Gibbs free energy is a state function.
d) For an endothermic process, ΔH is negative.
e) If the work done by the system is greater than the heat absorbed by the system, ΔE is nega-
tive.
2. The standard Gibbs free energy change of a reaction depends on the equilibri-
um______________________?
a) Pressure
b) Temperature
c) Composition
d) All A, B. and C
3. Which of the following defines Helmholtz function?
a) F = H + TS
b) F = H - TS
c) F = U - TS
d) F = U + TV
4. Equation which relates pressure, volume and temperature of a gas is called
the__________________?
a) Equation of state
b) Gibbs Duhem equation
c) Ideal gas equation
d) None of these
5. Which one of the following statements regarding energy is false?
a) The total energy in a chemical universe (a system and its surroundings) is constant
b) Energy can be converted from one form to another

2. Malik Xufyan WhatsApp # 0313-7355727
2 | P a g e
c) The energy stored in chemical bonds is referred to as kinetic energy
d) An object suspended in the air has more energy than an object lying on the ground
6. Which one of the following statements best describes the enthalpy change of a reac-
tion?
a) The energy released when chemical bonds are formed during a chemical reaction
b) The energy consumed when chemical bonds are broken during a chemical reaction
c) The difference between the energy released by bond formation and the energy consumed
by bond cleavage during a chemical reaction
d) The increase in disorder of the system as a reaction proceeds
7. In which direction does the transfer of energy as heat happen spontaneously?
a) From cold to hot
b) From hot to cold
8. The spontaneous nature of a reaction is impossible if :
a) D H is +ve, D S is also +ve
b) D H is – ve; D S is also – ve
c) D H is –ve ; D S is +ve
d) D H is +ve; D S is –ve
9. If D H > 0 and D S > 0, the reaction proceeds spontaneously when
a) D H > 0
b) D H < T D S
c) D H = TD S
d) None
10. The enthalpy change for a given reaction at 298 K is –x cal mol–1. If the reaction oc-
curs spontaneously at 298 K, the entropy change at that temperature
a) Can be negative but numerically larger than x/298 Cal K–1 mol–1
b) Can be negative but numerically smaller than x/298 Cal K–1 mol–1
c) Cannot be negative
d) Cannot be positive
11. A system suffers an increase in internal energy of 80 J and at the same time has 50 J
of work done on it. What is the heat change of the system?
a) +130 J
b) +30 J
c) -130 J
d) -30 J
12. All of the following have a standard heat of formation value of zero at 25oC and 1.0
atm except:
a) N2(g)
b) Fe(s)
c) Ne(g)
d) H(g)
13. For a spontaneous process, the change in Gibbs function is equal to the
a) the heat content of the system
b) entropy change of the system
c) work of expansion

3. Malik Xufyan WhatsApp # 0313-7355727
3 | P a g e
d) useful work
14. The melting of ice into liquid water is an example of tube _______________ reaction.
a) endergonic
b) exergonic
c) exothermic
d) endothermic
15. The Gibbs free energy is positive when a change in enthalpy and change in entropy
are positive at ____________
a) high temperatures
b) low temperature
c) all temperatures
d) only at 0 Kelvin
16. What is the relation between Gibbs free energy and the EMF of the cell?
a) ΔG = -nFEcell
b) G = -nFEcell
c) ΔG = -nEcell
d) ΔG = -nFcell
17. Calculate the Gibbs free energy for the conversion of oxygen to Ozone at room tem-
perature if KP is given as 2.47 x 10-29.
a) 163 kJ/mol
b) 163 J/mol
c) 163 kJ
d) 163 k/mol
18. Calculate the Gibbs free energy for the reaction of conversion of ATP into ADP at
293 Kelvin the change in enthalpy is 19.07 Kcal and the change in entropy is 90 cal per
Kelvin.
a) 7.3 cal
b) -5.3 Kcal
c) 7.3 Kcal
d) -7.3 Kcal
Chemical Equilibrium
19. Thermodynamic equilibrium is completely defined by the specifications of:
a) Internal energy
b) Enthalpy
c) Generalized displacements
d) All of above
20. The entropy of an isolated system always ____ and reaches ____ when equilibrium is
reached.
a) remains constant, maximum
b) decreases, minimum
c) increases, maximum
d) none of the mentioned

4. Malik Xufyan WhatsApp # 0313-7355727
4 | P a g e
21. Which of the following statement is true?
a) a system is in equilibrium state if, when it is disturbed, it comes back to its original state
b) if there is a spontaneous change in the state, the system is not in equilibrium
c) during a spontaneous change, the entropy of system increases
d) all of the mentioned
22. For a system to be in a state of neutral equilibrium
a) dS=dG=dF=0
b) dS=0, dG=dF<0
c) dS=0, dG=dF>0
d) none of the mentioned
23. A system is said to be in a state of unstable equilibrium when
a) dG<0, dF<0, dS<0
b) dG<0, dF<0, dS>0
c) dG>0, dF>0, dS>0
d) dG>0, dF>0, dS<0
24. In which of the following process, the process is always non-feasible?
a) ΔH > 0, ΔS > 0
b) ΔH < 0, ΔS > 0
c) ΔH > 0, ΔS < 0
d) ΔH < 0, ΔS < 0
25. A spontaneous process
a) is reversible.
b) is irreversible.
c) may be reversible or irreversible depending on whether equilibrium is maintained
throughout the process.
d) may be reversible or irreversible depending on the value of ΔS.
26. The Third Law of Thermodynamics states:
a) If object A is in thermal equilibrium with object B, and object B is in thermal equilibrium
with object C, then object A is in thermal equilibrium with object C.
b) The entropy of the universe increases for reversible processes.
c)ΔS = 0 for a pure element in its most stable state at standard conditions.
d) S = 0 for a perfect crystal of a pure substance at 0 K.
27. A reaction was found to be zero order in B. Increasing the concentration of B by a
factor of 3 would cause the reaction rate to
a) decrease by a factor of 9.
b) increase by a factor of 27.
c) increase by a factor of 3.
d) remain constant.
28. A reversible process is one that
a) is spontaneous in both directions.
b) occurs without any outside interventions.
c) must be carried out at low temperature.
d) can be reversed with no net change in either system or surroundings.

5. Malik Xufyan WhatsApp # 0313-7355727
5 | P a g e
29. What is the equation for entropy of a system if two parts 1 and 2 having entropies S1
and S2 are considered in equilibrium?
a) S = S1 – S2
b) S = S1 + S2
c) S = (S1 + S2) / 2
d) S = S1 S2
Concept of Residual Entropy
30. Residual entropy is the difference in entropy between a non-equilibrium state and
crystal state of a substance close to
a) 100 K
b) 1000 K
c) Absolute zero
d) 100 o
C
31. As the carbon monoxide crystal is cooled to absolute zero, few of the carbon
monoxide molecules have enough time to align themselves into a
a) Perfect crystal
b) Solid
c) Liquid
d) Semisolid
32. At the state of perfect order (W = 1) of pure crystalline substance, how is the zero
entropy defined?
a) entropy at 0 °C temperature
b) entropy at absolute zero temperature
c) entropy at the freezing point of the substance
d) none of the above
33. The entropy of CO at absolute zero is______
a) Positive
b) zero
c) increase
d) decrease
34. The Boltzmann entropy equation is________
(a) dS = dq/T
(b) S = Klnw
(c) ΔS = 0
(d) S = f(W)
35. Planck proposed the relationship between the entropy of a system and the
thermodynamic probability is given by the equation _______
(a)S=klnw
(b) S=kw
(c)S= -klnw
(d) S=klnT

6. Malik Xufyan WhatsApp # 0313-7355727
6 | P a g e
36. The third law of thermodynamics states that in the limit T→0
(a) G=0
(b) H=0
(c) V=0
(d) S=0
37. At the most probable state of a system the entropy of the system is
a) minimum
b) maximum
c) constant
d) none of the above
38. What is the entropy chosen at the triple point of water?
a) zero
b) less than zero
c) more than zero
d) none of the above
39. Which is the correct unit for entropy?
(a) kJ mol
(b) J K-1 mol-1
(c) J K-1mol
(d) kJ mol-1
40. The degree of disorder of a mixture of two gases
a) is always less than the degrees of disorder of individual gases
b) is always greater than the degrees of disorder of individual gases
c) is always equals the degrees of disorder of individual gases
d) none of the above