Thermodynamics PYQs Set 3 (PDF)

Set 3 of 14 · Questions 61-90 of 393

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Mere Teacher · Previous Year Questions NEET Chemistry · Thermodynamics · Set 3 (Q61-90)
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61. $Which of the following graphs correctly represents the variation of thermodynamic properties of Haber's process?$ (1) (2) (3) (4) 62. $Δ H and Δ S for a reaction are + 30.0 kJ mol^{- 1} and 0.06 kJK^{- 1} mol^{- 1} at 1 atm pressure. The temperature at which free energy change is equal to zero and nature of the reaction below this temperature are$ (1) $500^{\circ} C and non-spontaneous$ (2) $227^{\circ} C and non-spontaneous$ (3) $400^{\circ} C and spontaneous$ (4) $127^{\circ} C and spontaneous$ 63. $The number of extensive and intensive properties in the following list is respectively Mass, temperature, pressure, enthalpy, heat capacity, internal energy, density$ (1) $2,5$ (2) $3,4$ (3) $4.3$ (4) $5,2$ 64. $In which case change in entropy is negative?$ (1) $Evaporation of water$ (2) $Expansion of a gas at constant temperature$ (3) $Sublimation of solid to gas$ (4) $2 H (g) \to H_{2} (g)$ 65. $Bond dissociation enthalpy of H_{2}, C l_{2} and HC1 are 434, 242 and 431 kJmo l^{- 1} respectively Enthalpy of formation of HC1 is$ (1) $- 93 kJmo l^{- 1}$ (2) $245 kJmo l^{- 1}$ (3) $93 kJmo l^{- 1}$ (4) $- 245 kJmo l^{- 1}$ 66. $What is the standard enthalpy of reaction (in kJ) when two moles of Fe_{2} O_{3} (s) reacts with H_{2} gas to give Fe metal? Δ H_{f}^{\circ} of Fe_{2} O_{3} (s) and H_{2} O (l) are -824.2 and - 285.83 kJ mol^{- 1} respectively.$ (1) $-66.58$ (2) $-33.3$ (3) $-538.37$ (4) $-1110.03$ 67. $For a reversible reaction: X_{(g)} + 3 Y_{(g)} \to 2 Z_{(g)} . Δ H = - 40 kJ, the standard entropies of X, Y and Z are 60,40 and 50 JK^{- 1} mol^{- 1} respectively. The temperature at which the above reaction attains equilibrium is about$ (1) $400 K$ (2) $500 K$ (3) $273 K$ (4) $373 K$ 68. $When the same quantity of heat is absorbed by a system at two different temperatures T_{1} and T_{2}, such that T_{1} > T_{2}, change in entropies are Δ S_{1} and Δ S_{2} respectively. Then$ (1) $Δ S_{1} = Δ S_{2}$ (2) $S_{2} > S_{1}$ (3) $Δ S_{2} < Δ S_{1}$ (4) $Δ S_{1} < Δ S_{2}$ 69. $What is the entropy change when 1 mole oxygen gas expands isothermally and reversibly from an initial volume of 10 L to 100 L at 300 K?$ (1) $19.14 J K^{- 1}$ (2) $109.12 J K^{- 1}$ (3) $29.12 J K^{- 1}$ (4) $10 J K^{- 1}$ 70. $For the reaction, H_{2} O (l) ⟶ H_{2} O (g) at T = 100^{\circ} C and p = 1 atm, choose the correct option.$ (1) $Δ S_{system} > 0 and Δ S_{surrounding} > 0$ (2) $Δ S_{system} > 0 and Δ S_{surrounding} < 0$ (3) $Δ S_{system} < 0 and Δ S_{surrounding} > 0$ (4) $Δ S_{system} < 0 and Δ S_{surrounding} < 0$ 71. $Calculate the work done during compression of 2 mol of an ideal gas from a volume of 1 m^{3} to 10 dm^{3} at 300 K against a pressure of 100 KPa .$ (1) $- 99 kJ$ (2) $+ 99 kJ$ (3) $+ 22.98 kJ$ (4) $- 22.98 kJ$ 72. $1 mole of an ideal gas at 2 5^{0} C is subjected to expand reversibly and adiabatically to ten times of its initial volume. Calculate the change in entropy during expansion (in J k^{-1} m o l^{-1})$ (1) $19.15$ (2) $- 19.15$ (3) $4.7$ (4) $Zero$ 73. $For which of the following reactions, DH is equal to DU?$ (1) $N_{2} (g) + 3 H_{2} (g) ® 2 N H_{3} (g)$ (2) $2HI(g) ® H_{2} (g) + I_{2} (g)$ (3) $2 S O_{2} (g) + O_{2} (g) ® 2 S O_{3} (g)$ (4) $2 N O_{2} (g) ® N_{2} O_{4} (g)$ 74. $2 moles of ideal gas at 27 C temperature is expanded reversibly from 2 lit . to 20 lit . Find entropy change. (R = 2 cal/mol K)$ (1) $92.1$ (2) $0$ (3) $4$ (4) $9.2$ 75. $For the reaction at 25^{\circ} C, X_{2} O_{4} (l) ⟶ 2 XO_{2} (g), Δ U and Δ S are 2.1 K . Cal and 20 Cal / K respectively. What is Δ G for the reaction at the same temperature? (R = 2 Cal (K^{- 1} mol^{- 1})$ (1) $- 2.67 k . Cal$ (2) $+ 2.67 k . Cal$ (3) $- 1.67 k . Cal$ (4) $+ 3.67 k . Cal$ 76. $If the standard enthalpy of sublimation (Δ_{sub} H^{\circ}) of solid CO_{2}, naphthalene, Li and Na are 25.2, 73.0, 162, 108 kJ mol respectively, the order of sublimation of these substances with temperature is .$ (1) $Na>Li> Naphthalene > Solid CO_{2}$ (2) $Solid CO_{2} > Na > Naphthalene > Li$ (3) $Solid CO_{2} > Naphthalene >Na>Li$ (4) $Li > Na > Naphthalene > Solid CO_{2} .$ 77. $Which one of the following is applicable for an adiabatic expansion of an ideal gas?$ (1) $Δ𝐸=0$ (2) $Δ𝑊=Δ𝐸$ (3) $Δ W = - Δ E$ (4) $Δ W = 0$ 78. $Calculate the total entropy change for the transition at 368 K of 1 mol of sulphur from the monoclinic to the rhombic solid state and ∆ H = - 401.7 J m o l^{-1} for the transition. Assume the surroundings to be an ice-water. Both at 0^{0} C:$ (1) $- 1.09 J K^{-1}$ (2) $1.47 J K^{-1}$ (3) $0.38 J K^{-1}$ (4) $None$ 79. $The standard reaction Gibbs energy for a chemical reaction at an absolute temperature T is given by Δ G ° = A - BT where A and B are non-zero constants. Which of the following is true about this reaction?$ (1) $Exothermic if B < 0$ (2) $Endothermic if A > 0$ (3) $Endothermic if A < 0 and B > 0$ (4) $Exothermic if A > 0 and B < 0$ 80. $Considering entropy (S) as a thermodynamic parameter, the criterion for the spontaneity of any process is$ (1) $Δ S_{system} + Δ S_{surroundings} > 0$ (2) $Δ S_{system} - Δ S_{surroundings} > 0$ (3) $Δ S_{system} > 0 only$ (4) $Δ S_{surroundings} > 0 only.$ 81. $If the standard enthalpy change (Δ_{r} H^{θ}) for reaction H_{2} (g) + Br_{2} (l) \to 2 HBr (g) is - 72.8 kJ, the standard enthalpy of formation (Δ_{f} H^{θ}) of HBr (g) () in (kJ mol^{- 1}) is$ (1) $-36.4$ (2) $+36.4$ (3) $-18.2$ (4) $-9.1$ 82. $A reaction at 1 bar is non-spontaneous at low temperature but becomes spontaneous at high temperature. Identify the correct statement about the reaction among the following:$ (1) $Both DH and DS are positive.$ (2) $DH is negative while DS is positive.$ (3) $DH is positive while DS is negative.$ (4) $Both DH and DS are negative.$ 83. $Two mole of an ideal gas is expanded irreversibly and isothermally at 3 7^{0} C until its volume is doubled and 3.41 kJ heat is absorbed from surrounding. ∆ S_{t o t a l} (system + surrounding) is :$ (1) $-0.52 J/K$ (2) $0.52 J/K$ (3) $22.52 J/K$ (4) $0$ 84. $Given that N_{2} (g) + 3 H_{2} (g) ⟶ 2 NH_{3} (g); Δ_{r} H^{\circ} = - 92 kJ, the standard molar enthalpy of formation in kJ mol^{- 1} of NH_{3} (g) is$ (1) $-92$ (2) $+46$ (3) $+92$ (4) $-46$ 85. $Which from following thermodynamic properties is a path function?$ (1) $Internal energy$ (2) $Work$ (3) $Entropy$ (4) $Enthalpy$ 86. $The enthalpy of formation of NH_{3} is - 46 kJ mol^{- 1} . The enthalpy change for the reaction: 2 NH_{3 (g)} ⟶ N_{2 (g)} + 3 H_{2 (g)} is$ (1) $+ 23 kJ$ (2) $+ 92 kJ$ (3) $+ 46 kJ$ (4) $+ 184 kJ$ 87. $If enthalpy change for following reaction at 300 K is + 7 kJ mol^{- 1} find the entropy change of surrounding? H_{2} O_{(s)} ⟶ H_{2} O_{(t)}$ (1) $- 42.8 J K^{- 1}$ (2) $- 23.3 JK^{- 1}$ (3) $- 30.7 J K^{- 1}$ (4) $- 110.0 JK^{- 1}$ 88. $One mole of which of the following has the highest entropy?$ (1) $Mercury$ (2) $Diamond$ (3) $Liquid nitrogen$ (4) $Hydrogen gas$ 89. $The ratio of heats liberated at 298 K from the combustion of one kg of coke and by burning water gas obtained from kg of coke is (Assume coke to be 100 % carbon) (Given : enthalpies of combustion of CO_{2}, CO and H_{2} as 393.5 kJ, 285 kJ, 285 kJ respectively all at 298 K).$ (1) $0.79 : 1$ (2) $0.69 : 1$ (3) $0.86 : 1$ (4) $0.96 : 1$ 90. $Which of the following relation is not correct ?$ (1) $∆ H = ∆ U-P ∆ V$ (2) $∆ U = q + W$ (3) $∆ S_{sy s} + ∆ S_{s u r r} > 0$ (4) $∆ G = ∆ H - T ∆ S$