JEE Questions for Chemistry Thermodynamics Quiz 4 - MCQExams.com

Which one of the following is correct ?
  • -∆G = ∆H - T∆S
  • ∆H = [∆G - T∆S]

  • Chemistry-Thermodynamics-8695.png

  • Chemistry-Thermodynamics-8696.png
What will be the temperature at which
∆G = -5. 2 kJ mol-1,∆H=145. 6 kJ mo1-1 and
∆S = 216 JK-1 mol-1 for a chemical reaction ?
  • 650 K
  • 425°C
  • 525 K
  • 625°C
In a fuel cell methanol is used as fuel and oxygen gas is used as an oxidiser. The reaction is
CH3 OH(l)+ 3⁄2 O2 (g)→CO2 (g) + 2H2O(l).
At 298 K standard Gibb's energies of formation for CH3 OH(l), H2O (l) and CO2 (g) are -166.2, -237.2 and -394.4 kJ mol-1 respectively. If standard enthalpy of combustion of methanol is -726 kJ mol-1 , efficiency of the fuel cell will be
  • 80%
  • 87%
  • 90%
  • 97%

Chemistry-Thermodynamics-8697.png
  • ∆H = 0
  • ∆E = 0
  • ∆H = T∆S
  • ∆H = ∆E
Given that dE = TdS - pdV and H = E + pV. Which one of the following relations is true ?
  • dH = TdS + Vdp
  • dH = SdT + Vdp
  • dH = -SdT + Vdp
  • dH = dE + pdV
  • dH = dE - TdS
The entropy of a perfectly crystalline material is zero at 0°C. This is statement of
  • first law of thermodynamics
  • second law of thermodynamics
  • third law of thermodynamics
  • law of conservation of energy
I2(s) ⇌ I2(g) ; ∆H = + 40 kcal, ∆S = 80 cal. The sublimation point of I2(s) will be
  • 100°C
  • 127°C
  • 227°C
  • 500°C

Chemistry-Thermodynamics-8699.png
  • 1250 K
  • 500 K
  • 750 K
  • 1000 K
The standard free energy change of a reaction is ∆G° = -115 kJ at 298 K. Calculate the equilibrium constant Kp in log Kp [R = 8.314 JK-1 mol-1 ]
  • 20.16
  • 2.303
  • 2.016
  • 13.83
If an endothermic reaction occurs spontaneously at constant temperature (T) and pressure (p), then which of the following is true ?
  • ∆G > 0
  • ∆H < 0
  • ∆S > 0
  • ∆S < 0
A spontaneous process is one in which the system suffers
  • no energy change
  • a lowering of free energy
  • a lowering of entropy
  • an increase in internal energy
When compared to ∆G° for the formation of Al2O3, the ∆G° for the formation of Cr2O3 is
  • higher
  • lower
  • same
  • unpredicted
For a reaction to be spontaneous at all temperatures
  • ∆G and ∆H should be negative
  • ∆G and ∆H should be positive
  • ∆G = ∆S = 0
  • ∆H < ∆G
The latent heat of fusion of ice at 0° C is 80 cal/g. Entropy change (∆S) accompanying the melting of 1 g of ice at 0° C would be (units cal/g/K)
  • 273
  • 8.0
  • 0.9
  • 0.293
For the process H2O(l) (1 bar, 273 K) ⇌ H2O(g ) (1 bar, 273 K) the correct set of thermodynamic parameters is
  • ∆G = 0, ∆S = +ve
  • ∆G = 0, ∆S = -ve
  • ∆G = +ve, ∆S = 0
  • ∆G = -ve, ∆S = +ve
In which of the following process, maximum increase in entropy is observed ?
  • Melting of ice
  • Sublimation of naphthalene
  • Condensation of water
  • Dissolution of salt in water
All naturally occurring process, proceed in a direction, which leads to
  • increase of enthalpy
  • increase of free energy
  • decrease of free energy
  • decrease of entropy
Considering the reaction,
C(s) + O2 (g) → CO2 (g) + 393.5 kJ the signs of ∆H, ∆S and ∆G respectively are
  • + , - , -
  • - , + , +
  • - , - , -
  • - , + , -
If ∆H = - 25 kcal, T = 300 K and ∆S = 9 cal, then the reaction is
  • spontaneous
  • non-spontaneous
  • equilibrium state
  • None of these
The free energy change ∆G = 0 when
  • the reactants are completely consumed
  • a catalyst is added
  • the system is at equilibrium
  • the reactants are initially mixed
For a reaction ∆H = (+3 kJ ), ∆S = (+ 10 J/ K) beyond which temperature this reaction will be spontaneous ?
  • 300 K
  • 200 K
  • 273 K
  • 373 K
For a spontaneous reaction the ∆G, equilibrium constant (K) and E°cell will be respectively,
  • -ve, >1, - ve
  • -ve, <1, - ve
  • +ve, >1, - ve
  • -ve, >1, + ve
For a system in equilibrium, ∆G = 0 under conditions of constant
  • temperature and pressure
  • temperature and volume
  • pressure and volume
  • energy and volume
Molar heat of vaporisation of a liquid is 6 kJ mol-1 . If the entropy change is 16 J mol-1 K-1 , the boiling point of the liquid is
  • 375° C
  • 375 K
  • 273 K
  • 102° C
∆H and ∆S for a reaction are + 30.558 kJ mol-1 and 0.066 kJ K-1 mol-1 at 1 atm pressure. The temperature at which free energy change is equal to zero and the nature of the reaction below this temperature are
  • 483 K, spontaneous
  • 443 K, non-spontaneous
  • 443 K, spontaneous
  • 463 K, non-spontaneous
  • 463 K, spontaneous
The free energy for a reaction having ∆H = 31400 cal, ∆S = 32 cal K-1 mol-1 at 1000° C is
  • - 9336 cal
  • - 7386 cal
  • - 1936 cal
  • + 9336 cal
∆G° vs T plot in the Ellingham's diagram slopes upwards for the reactions

  • Chemistry-Thermodynamics-8702.png
  • 2)
    Chemistry-Thermodynamics-8703.png

  • Chemistry-Thermodynamics-8704.png

  • Chemistry-Thermodynamics-8705.png
Considering entropy (S) as a thermodynamic parameter the criterion for the spontaneity of any process is
  • ∆Ssystem + ∆Ssurroundings > 0
  • ∆Ssystem - ∆Ssurroundings > 0
  • ∆Ssystem > 0 only
  • ∆Ssurroundings > 0 only
The correct relationship between free energy change in a reaction and the corresponding equilibrium constant Kc , is
  • ∆G = RT ln Kc
  • - ∆G = RT ln Kc
  • ∆G° = RT ln Kc
  • - ∆G° = RT ln Kc
In the reaction C(s) + O2 (g) → CO2 (g) + 93.4 kcal
  • Enthalpy of products is greater than that of reactants
  • Enthalpy of products is less than that of reactants
  • Enthalpy of products is same as that of reactants
  • Enthalpy of products is half of that of reactants.
∆E is the heat absorbed at constant
  • temperature (T)
  • pressure (P)
  • volume (V)
  • T, P and V
Look at the following diagram:
The enthalpy change for the reaction A → B will be
Chemistry-Thermodynamics-8706.png
  • -25 kJ
  • -40 kJ
  • +25 kJ
  • – 65 kJ
The heat formation of H2O (l) is — 68.0 kcal, the heat of formation of H2O (g) is likely to be
  • – 68.0 kcal
  • – 69.4 kcal
  • 80.0 kcal
  • – 58.3 kcal
The heats of neutralisation of four acids a, b, c and d when neutralised against a common base are 13.7, 9.4, 11.2 and 12.4 kcal respectively. The weakest among these acids is
  • a
  • b
  • c
  • d
In a reversible process, ∆Ssys + ∆Ssurr is
  • > 0
  • < 0
  • ≥ 0
  • = 0
Which of the following expressions defines the physical significance of free energy change ?
  • ∆G = w(non exp)
  • –∆G = w(non exp)
  • ∆G = – w(exp.)
  • ∆G = w(exp.)
Which of the following relationship is correct ?
  • ∆Go = −RT ln K
  • K = e-∆Go/RT
  • K = 10-∆Go/2.303 RT
  • All are correct
Which one is true ?
  • 1 calorie > 1 erg > 1 Joule
  • 1 erg > 1 calorie > 1 Joule
  • 1 calorie > 1 Joule > 1 erg
  • 1 Joule > 1 calorie > 1 erg
A gas is allowed to expand under adiabatic conditions. What is zero for such a process ?
  • ∆G
  • ∆T
  • ∆S
  • none of these
A system changes from state A (P1,V1,T1) to B (P2,V2, T2 ) to C (P3,V3, T3) and then back to A. The complete process is called
  • Reversible process
  • Cyclic process
  • Spontaneous process
  • Isobaric process
Which of the following units represents largest amount of energy ?
  • Calorie
  • Joule
  • Erg
  • Electron volt
A spontaneous change is one in which the system suffers
  • An increase in internal energy
  • A lowering of entropy
  • A lowering of free energy
  • No energy change
Heat of neutralization of NH4OH and HCl is
  • 13.7 kcal/mole
  • <13.7 kcal/mole
  • >13.7 kcal/mole
  • zero
Equal volumes of molar hydrochloric acid and sulphuric acid are neutralized by dil. NaOH solution and x kcal and y kcal of heat are liberated respectively. Which of the following is true ?
  • x = y
  • x = 1/2y
  • x = 2y
  • None of these

Chemistry-Thermodynamics-8715.png
  • ∆S = O
  • ∆H = ∆O
  • ∆H = ∆E
  • ∆H = T∆S
Which one of the following bonds has the highest average bond energy (kcal/mole)?
  • S = O
  • C = C
  • C ≡ N
  • N ≡ N
Identify the state function among the following
  • q
  • q – w
  • q / w
  • q + w
In the reaction CO2(g) + H2(g) → CO2(g) + H2O(g); ∆H = 2.8 kJ ∆H represents
  • heat of reaction
  • heat of combustion
  • heat of formation
  • heat of solution
The energy change of reaction C2H6(g) → 2C(g) + 6H(g) is X kJ.The bond energy of C – H bond is
  • X/6kJ
  • X/3 kJ
  • X kJ
  • Indeterminate
The enthalpy of nutralistion of a weak acid by a strong base is
  • – 57 .32 kJ
  • +57.32 kJ
  • equal to – 57.32 k J + enthalpy of ionization of weak acid
  • more than – 57.32 kJ
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