JEE Main & Advanced Chemistry Thermodynamics / रासायनिक उष्मागतिकी Question Bank

done Free energy and work function Total Questions - 28

• question_answer1)
  The free energy change for a reversible reaction at equilibrium is [NCERT 1984; Kurukshetra CEE 1998;  AMU 1999]
  A)
                  Large positive    done clear
  B)
                  Small negative done clear
  C)
                  Small positive    done clear
  D)
                  0 done clear
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• question_answer2)
  For a spontaneous change, free energy change \[\Delta G\] is [MNR 1983; BHU 1981, 95; AMU 1999; DCE 2000, 01; BHU 2000; MP PMT 2003]
  A)
                  Positive done clear
  B)
                  Negative done clear
  C)
                  Zero done clear
  D)
                  Can be positive or negative done clear
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• question_answer3)
  A minus sign of the free energy change denotes that
  A)
                  The reaction tends to proceed spontaneously done clear
  B)
                  The reaction is non-spontaneous done clear
  C)
                  The system is in equilibrium done clear
  D)
                  The reaction is very much unlikely done clear
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• question_answer4)
  The relation between \[\Delta G\] and \[\Delta H\] is [MP PMT 1994, 95, 97; AFMC 1997; Kurukshetra CEE 1998]
  A)
                  \[\Delta H=\Delta G-T\,\Delta S\]             done clear
  B)
                  \[\Delta G=\Delta H-T\,\Delta S\] done clear
  C)
                  \[T\,\Delta S-\Delta G=\Delta H\]             done clear
  D)
                  \[\Delta H=T\,\Delta G+\Delta S\] done clear
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• question_answer5)
  At 300 K, the reactions which have following values of thermodynamic parameters occur spontaneously [Roorkee 1999]
  A)
                  \[\Delta {{G}^{o}}=-400\,\,kJ\,\,mo{{l}^{-1}}\] done clear
  B)
                  \[\Delta {{H}^{o}}=200\,\,kJ\,\,mo{{l}^{-1}},\,\,\,\Delta {{S}^{o}}=-4\,\,J{{K}^{-1}}mo{{l}^{-1}}\] done clear
  C)
                  \[\Delta {{H}^{o}}=-200\,kJ\,mo{{l}^{-1}},\,\,\Delta {{S}^{o}}=4\,J{{K}^{-1}}mo{{l}^{-1}}\] done clear
  D)
                  \[\Delta {{H}^{o}}=200\,J\,mo{{l}^{-1}},\,\,\Delta {{S}^{o}}=40\,J{{K}^{-1}}mo{{l}^{-1}}\] done clear
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• question_answer6)
  The relation \[\Delta G=\Delta H-T\Delta S\] was given by [MP PMT 2000; KCET 2002]
  A)
                  Boltzmann          done clear
  B)
                  Faraday done clear
  C)
                  Gibbs?Helmholtz             done clear
  D)
                  Thomson done clear
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• question_answer7)
  For precipitation reaction of \[A{{g}^{+}}\] ions with \[NaCl\], which of the following statements is correct           [CPMT 1988]
  A)
                  \[\Delta H\] for the reaction is zero done clear
  B)
                  \[\Delta G\] for the reaction is zero done clear
  C)
                  \[\Delta G\] for the reaction is negative done clear
  D)
                  \[[\Delta G]=[\Delta H]\] done clear
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• question_answer8)
  At constant pressure and temperature, the direction to the result of any chemical reaction is where, there is less amount of
  A)
                  Entropy                done clear
  B)
                  Enthalpy done clear
  C)
                  Gibb's free energy          done clear
  D)
                  None of the above done clear
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• question_answer9)
  The dependence of Gibbs free energy on pressure for an isothermal process of an ideal gas is given by [MP PET 1996]
  A)
                  \[\Delta {{G}_{T}}=nRT\,\ln \,\frac{{{P}_{2}}}{{{P}_{1}}}\]             done clear
  B)
                  \[\Delta {{G}_{T}}=nRT\,\ln \frac{{{V}_{2}}}{{{V}_{1}}}\] done clear
  C)
                  \[\Delta {{G}_{T}}=nRT\,\log \,\frac{{{P}_{1}}}{{{P}_{2}}}\]           done clear
  D)
                  \[\Delta {{G}_{T}}=nRT\,\log \,\frac{{{V}_{2}}}{{{V}_{1}}}\] done clear
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• question_answer10)
  For the change \[{{H}_{2}}O(l)\to {{H}_{2}}O(g);\,P=1\,atm\], \[T=373\,K\], the free energy change \[\Delta G=0\]. This indicates that
  A)
                  \[{{H}_{2}}O(l)\] is in equilibrium with \[{{H}_{2}}O(g)\] done clear
  B)
                  Water boils spontaneously at \[373\,K\] done clear
  C)
                  Water does not boil spontaneously at \[373\,K\] done clear
  D)
                  Condensation of water vapour occurs spontaneously at \[373\,K\] done clear
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• question_answer11)
  What is the free energy change \[\Delta G\] when \[1.0\,mole\] of water at \[{{100}^{o}}C\] and \[1\,atm\] pressure is converted into steam at \[{{100}^{o}}C\] and \[1\,atm\] pressure        [MP PET/PMT 1998]
  A)
                  \[540\,cal\]         done clear
  B)
                  \[-9800\,cal\] done clear
  C)
                  \[9800\,cal\]       done clear
  D)
                  \[0\,cal\] done clear
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• question_answer12)
  \[\Delta {{G}^{o}}\] for the reaction \[X+Y\]⇌ Z is ? 4.606 kcal . The value of equilibrium constant of the reaction at \[{{227}^{o}}C\] is \[(R=2.0\,cal.\,mo{{l}^{-1}}{{K}^{-1}})\]            [Roorkee 1999]
  A)
                  100 done clear
  B)
                  10 done clear
  C)
                  2              done clear
  D)
                  0.01 done clear
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• question_answer13)
  The standard enthalpy of the decomposition of \[{{N}_{2}}{{O}_{4}}\] to \[N{{O}_{2}}\] is 58.04 kJ and standard entropy of this reaction is 176.7 J/K. The standard free energy change for this reaction at \[{{25}^{o}}C\] is           [AIIMS 1999]
  A)
                  539 kJ    done clear
  B)
                  ? 539 kJ done clear
  C)
                  ? 5.39 kJ               done clear
  D)
                  5.39 kJ done clear
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• question_answer14)
  Spontaneity of a chemical reaction is decided by the negative change in                [MP PET 2001]
  A)
                  Internal energy done clear
  B)
                  Enthalpy done clear
  C)
                  Entropy                done clear
  D)
                  Free energy done clear
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• question_answer15)
  For a reaction at \[{{25}^{o}}C\] enthalpy change and entropy changes are \[-11.7\times {{10}^{3}}J\,mo{{l}^{-1}}\] and \[-105\,J\,mo{{l}^{-1}}{{K}^{-1}}\] respectively. What is the Gibbs free energy           [BHU 2001]
  A)
                  15.05 kJ done clear
  B)
                  19.59 kJ done clear
  C)
                  2.55 kJ   done clear
  D)
                   22.55 kJ done clear
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• question_answer16)
  Born-Haber cycle is used to determine  [UPSEAT 2001]
  A)
                  Crystal energy   done clear
  B)
                  Electron affinity done clear
  C)
                  Lattice energy   done clear
  D)
                  All of these done clear
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• question_answer17)
  Gibbs free energy G, enthalpy H and entropy S are interrelated as in      [MP PMT 2002]
  A)
                  \[G=H+TS\]        done clear
  B)
                  \[G=H-TS\] done clear
  C)
                  \[G-TS=H\]         done clear
  D)
                  \[G=S=H\] done clear
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• question_answer18)
  The essential condition for the feasibility of a reaction is that [JIPMER 2002]
  A)
                  The reaction should be exothermic done clear
  B)
                  The entropy of products must be larger than that of reactants done clear
  C)
                  The reaction is to be accompanied with free energy decrease done clear
  D)
                  The reaction has to possess high activation energy done clear
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• question_answer19)
  The correct relationship between free energy change in a reaction and the corresponding equilibrium constant \[{{K}_{c}}\] is [AIEEE 2003]
  A)
                  \[\Delta G=RT\ln {{K}_{c}}\]        done clear
  B)
                  \[-\Delta G=RT\ln {{K}_{c}}\] done clear
  C)
                  \[\Delta {{G}^{o}}=RT\ln {{K}_{c}}\]         done clear
  D)
                  \[-\Delta {{G}^{o}}=RT\ln {{K}_{c}}\] done clear
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• question_answer20)
  In an irreversible process taking place at constant T and P and in which only pressure-volume work is being done, the change in Gibbs free energy \[(dG)\] and change in entropy \[(dS)\], satisfy the criteria                [AIEEE 2003]
  A)
                  \[{{(dS)}_{V,\,E}}<0,\,{{(dG)}_{T,\,P}}<0\] done clear
  B)
                  \[{{(dS)}_{V,\,E}}>0,\,{{(dG)}_{T,\,P}}<0\] done clear
  C)
                  \[{{(dS)}_{V,\,E}}=0,\,{{(dG)}_{T,\,P}}=0\] done clear
  D)
                  \[{{(dS)}_{V,\,E}}=0,\,{{(dG)}_{T,\,P}}>0\] done clear
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• question_answer21)
  The densities of graphite and diamond at 298 K  are 2.25 and 3.31 g cm?3,  respectively. If the standard free energy difference \[(\Delta {{G}^{o}})\] is equal to 1895 J \[mo{{l}^{-1}}\], the pressure at which graphite will be transformed diamond at 298 K is [CBSE PMT 2003]
  A)
                  \[9.92\times {{10}^{5}}Pa\]         done clear
  B)
                  \[9.92\times {{10}^{8}}Pa\] done clear
  C)
                  \[9.92\times {{10}^{7}}Pa\]         done clear
  D)
                  \[9.92\times {{10}^{6}}Pa\] done clear
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• question_answer22)
  The free energy change for the following reactions are given below, \[{{C}_{2}}{{H}_{2}}(g)+\frac{5}{2}{{O}_{2}}(g)\,\to \]\[2C{{O}_{2}}(g)+{{H}_{2}}O(l);\,\Delta {{G}^{o}}=-1234\,kJ\] \[C(s)+{{O}_{2}}(g)\,\to C{{O}_{2}}(g)\,\,\Delta {{G}^{o}}=-394\,kJ\] \[{{H}_{2}}(g)+\frac{1}{2}{{O}_{2}}(g)\,\to \,{{H}_{2}}O(l)\,\,\,\Delta {{G}^{o}}=-237kJ\] What is the standard free energy change for the reaction \[{{H}_{2}}(g)+2\,C\,(s)\to {{C}_{2}}{{H}_{2}}(g)\]                                        [Kerala (Med.) 2002]
  A)
                  ? 209 kJ done clear
  B)
                  ? 2259 kJ done clear
  C)
                  + 2259 kJ              done clear
  D)
                  209 kJ done clear
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• question_answer23)
  The equilibrium concentration of the species in the reaction \[A+B\equiv C+D\] are 3, 5, 10 and 15 \[mole\,{{L}^{-1}}\] respectively at \[300\,K\] the \[\Delta G\] for the reaction is       [Pb. PMT 2004]
  A)
                  13.81     done clear
  B)
                  ? 1381.8 done clear
  C)
                  ? 138.18               done clear
  D)
                  1391.6 done clear
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• question_answer24)
  Gibb?s free enrgy \[(G)\] is defined as   [Pb. CET 2001]
  A)
                  \[\Delta G=\Delta H-T\Delta S\] done clear
  B)
                  \[\Delta G=\Delta H+\frac{T}{\Delta S}\] done clear
  C)
                  \[\Delta H=\Delta G-T\Delta S\] done clear
  D)
                  \[\Delta G=\Delta H+T.{{C}_{p}}\] done clear
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• question_answer25)
  Standard enthalpy and standard entropy changes for the oxidation of ammonia at \[298\,K\] are \[-382.64\,kJ\,mo{{l}^{-1}}\] and \[-145.6\,J{{K}^{-1}}mo{{l}^{-1}}\], respectively. Standard Gibbs energy change  for the same reaction at \[298\,K\] is [CBSE PMT 2004]
  A)
                  ? 439.3 kJ \[mo{{l}^{-1}}\]            done clear
  B)
                  ? 523.2 \[kJ\,mo{{l}^{-1}}\] done clear
  C)
                  ? 221.1 \[kJ\,mo{{l}^{-1}}\]          done clear
  D)
                  ? 339.3 \[kJ\,mo{{l}^{-1}}\] done clear
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• question_answer26)
  For spontaneity of a cell, which is correct [Orissa JEE 2004]
  A)
                  \[\Delta G=0,\,\Delta E=0\] done clear
  B)
                  \[\Delta G=-ve,\,\Delta E=0\] done clear
  C)
                  \[\Delta G=+ve,\,\Delta E=+ve\] done clear
  D)
                  \[\Delta G=-ve,\,\Delta E=+ve\] done clear
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• question_answer27)
  The free energy for a reaction having \[\Delta H=31400\,ca;\]. \[\Delta S=32\,cal\,{{K}^{-1}}\,mo{{l}^{-1}}\] at \[{{1000}^{o}}C\] is         [Orissa JEE 2005]
  A)
                  ? 9336 cal            done clear
  B)
                  ? 7386 cal done clear
  C)
                  ?1936 cal             done clear
  D)
                  + 9336 cal done clear
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• question_answer28)
  The \[\Delta H\] and \[\Delta S\] for a reaction at one atmospheric pressure are +30.558 kJ and \[0.066\,kJ{{k}^{-1}}\] respectively. The temperature at which the free energy change will be zero and below of this temperature the nature of reaction would be      [Kerala CET 2005]
  A)
                  483 K, spontaneous done clear
  B)
                  443 K, non-spontaneous done clear
  C)
                  443 K, spontaneous done clear
  D)
                  463 K, non-spontaneous done clear
  E)
                  463 K, spontaneous done clear
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