Thermodynamics PYQs Set 4 (PDF)

Set 4 of 18 · Questions 91-120 of 511

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Mere Teacher · Previous Year Questions JEE Main Chemistry · Thermodynamics · Set 4 (Q91-120)
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91. $Which one of the following is applicable for an adiabatic expansion of an ideal gas?$ (1) $Δ𝐸=0$ (2) $Δ𝑊=Δ𝐸$ (3) $Δ W = - Δ E$ (4) $Δ W = 0$ 92. $Calculate the total entropy change for the transition at 368 K of 1 mol of sulphur from the monoclinic to the rhombic solid state and ∆ H = - 401.7 J m o l^{-1} for the transition. Assume the surroundings to be an ice-water. Both at 0^{0} C:$ (1) $- 1.09 J K^{-1}$ (2) $1.47 J K^{-1}$ (3) $0.38 J K^{-1}$ (4) $None$ 93. $The standard reaction Gibbs energy for a chemical reaction at an absolute temperature T is given by Δ G ° = A - BT where A and B are non-zero constants. Which of the following is true about this reaction?$ (1) $Exothermic if B < 0$ (2) $Endothermic if A > 0$ (3) $Endothermic if A < 0 and B > 0$ (4) $Exothermic if A > 0 and B < 0$ 94. $Considering entropy (S) as a thermodynamic parameter, the criterion for the spontaneity of any process is$ (1) $Δ S_{system} + Δ S_{surroundings} > 0$ (2) $Δ S_{system} - Δ S_{surroundings} > 0$ (3) $Δ S_{system} > 0 only$ (4) $Δ S_{surroundings} > 0 only.$ 95. $If the standard enthalpy change (Δ_{r} H^{θ}) for reaction H_{2} (g) + Br_{2} (l) \to 2 HBr (g) is - 72.8 kJ, the standard enthalpy of formation (Δ_{f} H^{θ}) of HBr (g) () in (kJ mol^{- 1}) is$ (1) $-36.4$ (2) $+36.4$ (3) $-18.2$ (4) $-9.1$ 96. $A reaction at 1 bar is non-spontaneous at low temperature but becomes spontaneous at high temperature. Identify the correct statement about the reaction among the following:$ (1) $Both DH and DS are positive.$ (2) $DH is negative while DS is positive.$ (3) $DH is positive while DS is negative.$ (4) $Both DH and DS are negative.$ 97. $Two mole of an ideal gas is expanded irreversibly and isothermally at 3 7^{0} C until its volume is doubled and 3.41 kJ heat is absorbed from surrounding. ∆ S_{t o t a l} (system + surrounding) is :$ (1) $-0.52 J/K$ (2) $0.52 J/K$ (3) $22.52 J/K$ (4) $0$ 98. $Given that N_{2} (g) + 3 H_{2} (g) ⟶ 2 NH_{3} (g); Δ_{r} H^{\circ} = - 92 kJ, the standard molar enthalpy of formation in kJ mol^{- 1} of NH_{3} (g) is$ (1) $-92$ (2) $+46$ (3) $+92$ (4) $-46$ 99. $Which from following thermodynamic properties is a path function?$ (1) $Internal energy$ (2) $Work$ (3) $Entropy$ (4) $Enthalpy$ 100. $The enthalpy of formation of NH_{3} is - 46 kJ mol^{- 1} . The enthalpy change for the reaction: 2 NH_{3 (g)} ⟶ N_{2 (g)} + 3 H_{2 (g)} is$ (1) $+ 23 kJ$ (2) $+ 92 kJ$ (3) $+ 46 kJ$ (4) $+ 184 kJ$ 101. $If enthalpy change for following reaction at 300 K is + 7 kJ mol^{- 1} find the entropy change of surrounding? H_{2} O_{(s)} ⟶ H_{2} O_{(t)}$ (1) $- 42.8 J K^{- 1}$ (2) $- 23.3 JK^{- 1}$ (3) $- 30.7 J K^{- 1}$ (4) $- 110.0 JK^{- 1}$ 102. $One mole of which of the following has the highest entropy?$ (1) $Mercury$ (2) $Diamond$ (3) $Liquid nitrogen$ (4) $Hydrogen gas$ 103. $The ratio of heats liberated at 298 K from the combustion of one kg of coke and by burning water gas obtained from kg of coke is (Assume coke to be 100 % carbon) (Given : enthalpies of combustion of CO_{2}, CO and H_{2} as 393.5 kJ, 285 kJ, 285 kJ respectively all at 298 K).$ (1) $0.79 : 1$ (2) $0.69 : 1$ (3) $0.86 : 1$ (4) $0.96 : 1$ 104. $Which of the following relation is not correct ?$ (1) $∆ H = ∆ U-P ∆ V$ (2) $∆ U = q + W$ (3) $∆ S_{sy s} + ∆ S_{s u r r} > 0$ (4) $∆ G = ∆ H - T ∆ S$ 105. $The work done when two moles of an ideal gas is compressed from a volume of 5 m^{3} to 1 dm^{3} at 300 K, under a pressure of 100 kPa is$ (1) $499.9 kJ$ (2) $- 499.9 kJ$ (3) $- 99.5 kJ$ (4) $42495 kJ$ 106. $The enthalpy of formation of ammonia when calculated from the following bond energy data is (B.E. of N - H, H - H, N \equiv N is 389 kJ , 389 k J m o l^{- 1}, 435 k J m o l^{- 1}, 945.36 k J m o l^{- 1} respectively)$ (1) $- 41.82 k J m o l^{- 1}$ (2) $+ 83.64 k J m o l^{- 1}$ (3) $- 945.36 k J m o l^{- 1}$ (4) $- 833 k J m o l^{- 1}$ 107. $Identify an extensive property amongst the following.$ (1) $Viscosity$ (2) $Heat capacity$ (3) $Density$ (4) $Surface tension$ 108. $For the reaction, C_{3} H_{8 (g)} + 5 O_{2 (g)} \to 3 C O_{2 (g)} + 4 H_{2} O_{(l)} at constant temperature, Δ H - Δ E is$ (1) $+RTv$ (2) $-3RT$ (3) $+3RT$ (4) $-RT$ 109. $Given that bond energies of H - H and Cl —Cl are 430 kJmo l^{- 1} and 240 kJmo l^{- 1} respectively and Δ H_{f} for HC1 is - 90 kJmo l^{- 1}, bond enthalpy of HC1 is$ (1) $380 kJmo l^{- 1}$ (2) $425 kJmo l^{- 1}$ (3) $245 kJmo l^{- 1}$ (4) $290 kJmo l^{- 1}$ 110. $For a sample of perfect gas when its pressure is changed isothermally from p_{i} to p_{f}, the entropy change is given by$ (1) $Δ S = nR ln (\frac{p _{f}}{p _{i}})$ (2) $Δ S = nR ln (\frac{p _{i}}{p _{f}})$ (3) $Δ S = nRT ln (\frac{p _{f}}{p _{i}}) (d) Δ S = RT ln (\frac{p _{i}}{p _{f}})$ 111. $If a chemical reaction is known to be non-spontaneous at 298 K but spontaneous at 350 K, then which among the following conditions is true for the reaction?$ (1) $Δ G = - ve, Δ H = - ve, Δ S = + ve$ (2) $Δ G = + ve, Δ H = + ve, Δ S = + ve$ (3) $Δ G = - ve, Δ H = + ve, Δ S = + ve$ (4) $Δ G = + ve, Δ H = + ve, Δ S = - ve$ 112. $The enthalpies of formation of gaseous N_{2} O and NO at 298 K are 82.0 and 90.0 KJ mol^{- 1} respectively. The enthalpy change of the reaction N_{2} O (g) + \frac{1}{2} O_{2} (g) \to 2 NO (g) is$ (1) $- 74 kJ$ (2) $+ 98 kJ$ (3) $+ 89 kJ$ (4) $- 47 kJ$ 113. $For a dimerization reaction, 2 A (g) \to A_{2} (g) at 298K, ∆U° = -20kJ mo 1^{- 1}, ∆S° = -30 JK^{- 1} mo 1^{- 1}, then the ∆ G° will be J.$ 114. $For the reaction 2 N O_{2} ( g) ⇌ N_{2} O_{4} ( g), when ΔS = -176. 0 J K^{- 1} and ΔH = -57.8 kJ m o l^{- 1}, the magnitude of ΔG at 298 K for the reaction is ____k J m o l^{- 1} . (Nearest integer)$ 115. $Five moles of an ideal gas at 293 K is expanded isothermally from an initial pressure of 2.1 MPa to 1.3 MP a against at constant external 4.3 MPa. The heat transferred in this process is ____ kJ mo l^{- 1} . (Rounded-off ofthe nearest integer) [Use R = 8.314 J mo l^{- 1} K^{- 1}]$ 116. $For the reaction : A (l) \to 2 B (g) ∆ U = 2.1 kcal, ∆ S = 20 cal / K, at T = 300 K. Hence ∆G (in kcal) is - X . Find the value of X .$ 117. $Consider the following data Heat of combustion of H_{2} (g) =-241.8 kJ m o l^{- 1} Heat of combustion of C (s) =-393.5 kJ m o l^{- 1} Heat of combustion of C_{2} H_{5} OH(a)=-1234.7 kJ m o l^{- 1} The heat of formation of C_{2} H_{5} OH(a) is (-)_____kJ m o l^{- 1} (Nearest integer).$ 118. $When equal volume of 1 MHCl and 1 MH_{2} SO_{4} are separately neutralised by excess volume of 1 MNaOH solution. x and y kJ of heat is liberated respectively. The value of y / x is_____$ 119. $For a certain thermochemical reaction M \to N at T = 400 K, Δ H^{⊖} = 77.2 kJ mol^{- 1}, Δ S = 122 JK^{- 1}, log equilibrium constant (log K) is_______\times 10^{- 1} .$ 120. $For complete combustion of ethene, C_{2} H_{4} ( g) + 3 O_{2} ( g) \to 2 C O_{2} ( g) + 2 H_{2} O(a) the amount of heat produced as measured in bomb calorimeter is 1406 kJ m o l^{- 1} at 300 K. The minimum value of T ∆ S needed to reach equilibrium is (-) kJ. (Nearest integer) Given: R = 8. 3 J K^{- l} m o l^{- 1}$