JEE Questions for Chemistry Thermodynamics Quiz 3 - MCQExams.com


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  • 2)
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If ∆E is the heat of reaction for
C2 H5 OH( l ) + 3O2 (g) →2CO2(g) + 3H2O( l )
at constant volume, then ∆H (heat of reaction at constant pressure), at constant temperature is
  • ∆H = ∆E + RT
  • ∆H = ∆E - RT
  • ∆H = ∆E - 2RT
  • ∆H = ∆E + 2RT
The heat of formations for CO2 (g), H2 O( l ) and CH4 (g) are - 400 kJ mol-1 , - 280 kJ mol-1 and -70 kJ mol-1 respectively. The heat of combustion of CH4 in kJ mol-1 is
  • 890
  • - 160
  • - 890
  • - 90
The bond dissociation energies of H2 , Cl2 and HCl are 104, 58 and 103 kcal mol-1 respectively. The enthalpy of formation of HCl would be
  • - 22 kcal mol-1
  • - 44 kcal mol-1
  • + 44 kcal mol-1
  • + 22 kcal mol-1
∆H for the reaction,
C(graphite) + 2H2 (g) → CH4 (g) at 298 K and 1 atm is - 17900 cal. The ∆E for the above conversion would be
  • -17900 cal
  • 17900 cal
  • 17304 cal
  • - 17304 cal
Assuming that water vapour is an ideal gas, the internal energy change (∆U)when 1 mole of water is vaporised at 1 bar pressure and 100° C, (Given, molar enthalpy of vaporisation of water at 1 bar and 373 K = 41 kJ mol-1 and R = 8.3 J mol-1 K-1 ) will be
  • 4.100 kJ mol-1
  • 3.7904 kJ mol-1
  • 37.904 kJ mol-1
  • 41.00 kJ mol-1

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  • - 261 kJ
  • + 103 kJ
  • + 261 kJ
  • - 103 kJ

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  • 286.6 kJ
  • 573.2 kJ
  • - 28.66 kJ
  • zero
For an ideal gas, the heat of reaction at constant pressure and constant volume are related as
  • H + E = pV
  • E = H + p∆V
  • qp = qv + ∆nRT
  • None of these
Consider the reaction, N2 + 3H2 → 2NH3 carried out at constant temperature and pressure. If ∆H and ∆U are the enthalpy and internal energy changes for the reaction, which of the following expressions is true?
  • ∆H > ∆U
  • ∆H < ∆U
  • ∆H = ∆U
  • ∆H = 0
The enthalpies of combustion of carbon and carbon monoxide are -393.5 and- 283 kJ mol-1 respectively. The enthalpy of formation of carbon monoxide per mole is
  • 110.5 kJ
  • 676.5 kJ
  • - 676.5 kJ
  • - 110.5 kJ
Calculate enthalpy for formation of ethylene from the following data
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  • 54.1 kJ
  • 44.8 kJ
  • 51.4 kJ
  • 48.4 kJ
(∆H - ∆U) for the formation of carbon monoxide (CO) from its elements at 298 K is (R = 8.314 JK-1 mol-1 )
  • -1238.78 J mol-1
  • 1238.78 J mol-1
  • -2477.57 mol-1
  • 2477.57 J mol-1
If heat of neutralisation of HCN with NaOH is -12.1 kJ and the heat of neutralisation of HCl by NaOH is -55.9 kJ/mol, then the energy of dissociation of HCN is
  • 43.8 kJ
  • -43.8 kJ
  • -68 kJ
  • 68 kJ
Heat of formation of SO2 is - 298kJ. What is the heat of combustion of 4 g of S ?
  • + 37 kJ
  • -37.25 kJ
  • +298 kJ
  • 18.6 kJ
The heats of combustion of carbon monoxide at constant pressure and at constant volume at 27° C will differ from one another by
  • 27 cal
  • 54 cal
  • 300 cal
  • 600 cal
For the reaction, A (g)+ 2B (g) → 2C (g)+ 3D (g) the change of enthalpy at 27° C is 19 kcal. The value of ∆E is
  • 21.2 kcal
  • 17.8 kcal
  • 18.4 kcal
  • 20.6 kcal
In an isochoric process, ∆H for a system is equal to
  • p . ∆V
  • pV
  • E + p . ∆V
  • ∆E
Which of the following indicates the heat of reaction equal to heat of formation ?
  • C (graphite) + O2 (1 atm) → CO2 (1 atm)
  • C (diamond) + O2 (1 atm) → CO2 (2 atm)
  • C (graphite) + O2 (1 atm) → CO2 (2 atm)
  • C (diamond) + O2 (1 atm) → CO2 (1 atm)
Calculate ∆H (in Joules) for, C (graphite) → C (diamond), from the following data
C (graphite) + O2 (g) → CO2 (g) ; ∆H = - 393.5 kJ
C (diamond) + O2 (g) → CO2 (g) ; ∆H = - 395.4 kJ
  • 1900
  • - 788.9 × 103
  • 190000
  • + 788.9 × 103

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  • 180 kJ mol-1
  • 360 kJ mol-1
  • 213 kJ mol-1
  • 425 kJ mol-1
For the reaction at 298 K. A(g)+ B(g) → C(g)
∆E = -5 cal and ∆S = -10 cal K-1
  • ∆G = +2612 cal
  • ∆G = -2612 cal
  • ∆G = +261.2 cal
  • None of these
The ∆H°f for CO2 (g), CO(g ) and H2O (g) are - 393.5, -110.5 and - 241.8 kJ / mol respectively. The standard enthalpy change (in kJ) for the reaction
CO2 (g) + H2 (g) → CO (g ) + H2O (g) is
  • 524.1
  • 41.2
  • - 262.5
  • - 41.2
The value of ∆E for combustion of 16 g of CH4 is - 885389 J at 298 K. The ∆H combustion for CH4 in J mol-1 at this temperature will be
(Given that, R = 8.314 JK-1mol-1)
  • - 55337
  • - 880430
  • - 885389
  • - 890348
If the bond dissociation energies of XY, X2 and Y2 (all diatomic molecules) are in the ratio of 1:1:0.5 and ∆Hf for the formation of XY is -200 kJ mol-1 . The bond dissociation energy of X2 will be
  • 400 kJ mol-1
  • 300 kJ mol-1
  • 20 kJ mol-1
  • None of these
For the reaction (at 1240 K and 1 atm.)
CaCO3 (s) → CaO(s) + CO2 (g)
∆H = 176 kJ /mol ; ∆E will be
  • 160 kJ
  • 165.6 kJ
  • 186.4 kJ
  • 180 kJ
Minimum work is obtained when 1 kg of ... gas expanded under 500 kPa to 200 kPa pressure at 0°C.
  • chlorine
  • oxygen
  • nitrogen
  • methane
Enthalpy of formation of HF and HCl are - 161 kJ and - 92 kJ respectively. Which of the following statements is incorrect ?
  • HCl is more stable than HF
  • HF and HCl are exothermic compounds
  • The affinity of fluorine to hydrogen is greater than the affinity of chlorine to hydrogen
  • HF is more stable than HCl
A mixture of two moles of carbon monoxide and one mole of oxygen, in a closed vessel is ignited to convert the carbon monoxide to carbon dioxide. If ∆H is the enthalpy change and ∆E is the change in internal energy, then
  • ∆H > ∆E
  • ∆H < ∆E
  • ∆H = ∆E
  • the relationship depends on the capacity of the vessel
The cooling in refrigerator is due to
  • reaction of the refrigerator gas
  • expansion of ice
  • the expansion of the gas in the refrigerator
  • the work of the compressor
What would be the heat released when an aqueous solution containing 0.5 mole of HNO3 is mixed with 0.3 mole of OH - (enthalpy of neutralisation is -57.1 kJ )?
  • 28.5 kJ
  • 17.1 kJ
  • 45.7 kJ
  • 1.7 kJ
  • 2.85 kJ
Maximum entropy will be in which of the following ?
  • Ice
  • Snow
  • Liquid water
  • Water vapours
Which of the following is not correct ?
  • Dissolution of NH4Cl in excess of water is an endothermic process
  • Neutralisation process is always exothermic
  • The absolute value of enthalpy (H) can be determined experimentally
  • The heat of reaction at constant volume is denoted by ∆E
For the process H2O( l ) → H2O (g )
at T =100° C and 1 atmosphere pressure, the correct choice is
  • ∆Ssystem > 0 and ∆Ssurrounding > 0
  • ∆Ssystem > 0 and ∆Ssurrounding < 0
  • ∆Ssystem < 0 and ∆Ssurrounding > 0
  • ∆Ssystem < 0 and ∆Ssurrounding < 0
For an ideal binary liquid mixture
  • ∆S(mix) = 0 ; ∆G(mix) = 0
  • ∆H(mix) = 0 ; ∆S(mix) < 0
  • ∆V(mix) = 0 ; ∆G(mix) > 0
  • ∆S(mix) > 0 ; ∆G(mix) < 0

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  • 2.48 V
  • 1.24 V
  • 2.5 V
  • 1.26 V
The values of ∆H and ∆S of a certain reaction are - 400 kJ mol-1 and - 20 kJ mol-1 K-1 respectively. The temperature below which the reaction is spontaneous, is
  • 100 K
  • 20°C
  • 20 K
  • 120°C
The temperature of K at which ∆G = 0, for a given reaction with ∆H = - 20.5 kJ mol-1 and ∆S = -50.0 JK-1 mol-1 is
  • - 410
  • 410
  • 2.44
  • - 2.44
Among the following for spontaneity of chemical reaction there should be
  • decrease in entropy and increase in free energy
  • decrease in entropy and free energy both
  • increase in entropy and decrease in free energy
  • increase in entropy and free energy both
One mole of ice is converted into water at 273 K. The entropies of H2O(s) and H2O(l) are 38.20 and 60.01 J mol-1 K-1 respectively. The enthalpy change for the conversion is
  • 3 kJ mol-1
  • 4 kJ mol-1
  • 5 kJ mol-1
  • 6 kJ mol-1
Which of the following processes is associated with decrease in entropy ?
  • Vaporisation of a mole of water into steam at its b.p.
  • Dissociation of a mole of common salt in water at 300 K
  • Mixing of two partially miscible liquids
  • Crystallisation of a salt from its saturated solution
Which of the following statements is true ?
  • The total entropy of the universe is continuously decreasing
  • The total energy of the universe is continuously decreasing
  • The total energy of the universe remains constant
  • The total entropy of the universe remains constant
Identify the correct statement from the following in a chemical reaction.
  • The entropy always increases
  • The change in entropy along with suitable change in enthalpy decides the rate of reaction
  • The enthalpy always decreases
  • Both the enthalpy and the entropy remain constant
For an isolated system, ∆U = 0, then
  • ∆S = 0
  • ∆S < 0
  • ∆S > 0
  • The values of ∆S cannot be predicted
The entropy change involved in the isothermal reversible expansion of 2 moles of an ideal gas from a volume of 10 dm3 to a volume of 100 dm3 at 27°C is
  • 38.3 J mol-1 K-1
  • 35.8 J mol-1 K-1
  • 32.3 J mol-1 K-1
  • 42.3 J mol-1 K-1
The enthalpy of vaporisation of benzene is +35.3 kJ/mol at its boiling point of 80°C. The entropy change in the transition of vapour to liquid at its boiling point is .... [in J mol-1 K-1].
  • - 100
  • + 100
  • + 342
  • - 342
For a particular reversible reaction at temperature T, ∆H and ∆S were found to be both +ve. If Te is the temperature at equilibrium, the reaction would be spontaneous when
  • Te > T
  • T >Te
  • Te is 5 times T
  • T = Te
When ice melts into water, the entropy
  • becomes zero
  • remains same
  • decreases
  • increases
If ∆G is negative, the reaction will be
  • at equilibrium
  • not possible
  • Both (and (2)
  • possible
During which phenomenon does entropy decrease ?
  • Crystallisation of sucrose from its solution
  • Melting of ice
  • Sublimation of camphor
  • Rusting of iron
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