Thermodynamics PYQs Set 3 (PDF)

Set 3 of 18 · Questions 61-90 of 511

In the print window choose “Save as PDF”. The file prints without a web address or date line.

Mere Teacher · Previous Year Questions JEE Main Chemistry · Thermodynamics · Set 3 (Q61-90)
Scan or visit mereteacher.com for free PYQ practice, timed CBT tests, step-by-step solutions and BroBot AI. Answers and solutions are free with a sign-up.
61. $In the reaction H_{2} O (l) \to H_{2} O (s) at 0^{\circ} C and 1 atm, the internal energy change is - 41 kJ / mol . What will be the value of molar enthalpy change?$ (1) $- 41 kJ / mol$ (2) $41 kJ / mol$ (3) $30 kJ / mol$ (4) $- 30 kJ / mol$ 62. $If one litre of an ideal gas at a pressure of 20 atm expands isothermally and reversibly to a final volume of ' X' L by absorbing 92.12 L . atm heat, ' X' (in L) is$ (1) $200$ (2) $20$ (3) $15$ (4) $100$ 63. $Identify the correct statement for change of Gibb’s energy for a system (Δ G_{system}) at constant temperature and pressure.$ (1) $If Δ G_{system} < 0, the process is not spontaneous.$ (2) $If Δ G_{system} > 0, the process is spontaneous.$ (3) $If Δ G_{system} = 0, the system has attained equilibrium.$ (4) $If Δ G_{system} = 0, the system is still moving in a particular direction.$ 64. $The enthalpy and entropy change for the reaction: B r_{2 (l)} + C l_{2 (g)} \to 2 BrC l_{(g)} are 30 kJmo l^{- 1} and 105 J K^{- 1} mo l^{-} respectively. The temperature at which the reaction will be in equilibrium is$ (1) $300 K$ (2) $285.7 K$ (3) $273 K$ (4) $450 K$ 65. $In which state, matter have highest entropy$ (1) $Solid$ (2) $Liquid$ (3) $Gas$ (4) $Equal in all$ 66. $Work done by an ideal gas at a constant volume is\dots\dots\dots$ (1) $- \frac{Δ p}{p}$ (2) $- V Δ p$ (3) $0$ (4) $\frac{nR}{p}$ 67. $Let us consider a reversible reaction at temperature, T. In this reaction, both Δ H and Δ S were observed to have positive values. If the equilibrium temperature is Te, then the reaction becomes spontaneous at:$ (1) $Te > T$ (2) $T > Te$ (3) $T = Te$ (4) $Te = 5 T$ 68. $Lattice enthalpy and enthalpy of solution of NaCl are 788kJ mol^{- 1} and 4kJ mol^{- 1}, respectively. The hydration enthalpy of NaCl is$ (1) $784kJ mol^{- 1}$ (2) $- 780 kJ mol^{- 1}$ (3) $780kJ mol^{- 1}$ (4) $- 784 kJ mol^{- 1}$ 69. $Which of the following graphs correctly represents the variation of thermodynamic properties of Haber's process?$ (1) (2) (3) (4) 70. $Δ H and Δ S for a reaction are + 30.0 kJ mol^{- 1} and 0.06 kJK^{- 1} mol^{- 1} at 1 atm pressure. The temperature at which free energy change is equal to zero and nature of the reaction below this temperature are$ (1) $500^{\circ} C and non-spontaneous$ (2) $227^{\circ} C and non-spontaneous$ (3) $400^{\circ} C and spontaneous$ (4) $127^{\circ} C and spontaneous$ 71. $The number of extensive and intensive properties in the following list is respectively Mass, temperature, pressure, enthalpy, heat capacity, internal energy, density$ (1) $2,5$ (2) $3,4$ (3) $4.3$ (4) $5,2$ 72. $In which case change in entropy is negative?$ (1) $Evaporation of water$ (2) $Expansion of a gas at constant temperature$ (3) $Sublimation of solid to gas$ (4) $2 H (g) \to H_{2} (g)$ 73. $Bond dissociation enthalpy of H_{2}, C l_{2} and HC1 are 434, 242 and 431 kJmo l^{- 1} respectively Enthalpy of formation of HC1 is$ (1) $- 93 kJmo l^{- 1}$ (2) $245 kJmo l^{- 1}$ (3) $93 kJmo l^{- 1}$ (4) $- 245 kJmo l^{- 1}$ 74. $What is the standard enthalpy of reaction (in kJ) when two moles of Fe_{2} O_{3} (s) reacts with H_{2} gas to give Fe metal? Δ H_{f}^{\circ} of Fe_{2} O_{3} (s) and H_{2} O (l) are -824.2 and - 285.83 kJ mol^{- 1} respectively.$ (1) $-66.58$ (2) $-33.3$ (3) $-538.37$ (4) $-1110.03$ 75. $For a reversible reaction: X_{(g)} + 3 Y_{(g)} \to 2 Z_{(g)} . Δ H = - 40 kJ, the standard entropies of X, Y and Z are 60,40 and 50 JK^{- 1} mol^{- 1} respectively. The temperature at which the above reaction attains equilibrium is about$ (1) $400 K$ (2) $500 K$ (3) $273 K$ (4) $373 K$ 76. $When the same quantity of heat is absorbed by a system at two different temperatures T_{1} and T_{2}, such that T_{1} > T_{2}, change in entropies are Δ S_{1} and Δ S_{2} respectively. Then$ (1) $Δ S_{1} = Δ S_{2}$ (2) $S_{2} > S_{1}$ (3) $Δ S_{2} < Δ S_{1}$ (4) $Δ S_{1} < Δ S_{2}$ 77. $What is the entropy change when 1 mole oxygen gas expands isothermally and reversibly from an initial volume of 10 L to 100 L at 300 K?$ (1) $19.14 J K^{- 1}$ (2) $109.12 J K^{- 1}$ (3) $29.12 J K^{- 1}$ (4) $10 J K^{- 1}$ 78. $Among the following, the state function(s) is(are) :$ (1) $Internal energy$ (2) $Irreversible expansion work$ (3) $Reversible expansion work$ (4) $Molar enthalpy$ 79. $For the reaction, H_{2} O (l) ⟶ H_{2} O (g) at T = 100^{\circ} C and p = 1 atm, choose the correct option.$ (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) $Δ S_{system} < 0 and Δ S_{surrounding} < 0$ 80. $Calculate the work done during compression of 2 mol of an ideal gas from a volume of 1 m^{3} to 10 dm^{3} at 300 K against a pressure of 100 KPa .$ (1) $- 99 kJ$ (2) $+ 99 kJ$ (3) $+ 22.98 kJ$ (4) $- 22.98 kJ$ 81. $1 mole of an ideal gas at 2 5^{0} C is subjected to expand reversibly and adiabatically to ten times of its initial volume. Calculate the change in entropy during expansion (in J k^{-1} m o l^{-1})$ (1) $19.15$ (2) $- 19.15$ (3) $4.7$ (4) $Zero$ 82. $For which of the following reactions, DH is equal to DU?$ (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) $2 N O_{2} (g) ® N_{2} O_{4} (g)$ 83. $2 moles of ideal gas at 27 C temperature is expanded reversibly from 2 lit . to 20 lit . Find entropy change. (R = 2 cal/mol K)$ (1) $92.1$ (2) $0$ (3) $4$ (4) $9.2$ 84. $For the reaction at 25^{\circ} C, X_{2} O_{4} (l) ⟶ 2 XO_{2} (g), Δ U and Δ S are 2.1 K . Cal and 20 Cal / K respectively. What is Δ G for the reaction at the same temperature? (R = 2 Cal (K^{- 1} mol^{- 1})$ (1) $- 2.67 k . Cal$ (2) $+ 2.67 k . Cal$ (3) $- 1.67 k . Cal$ (4) $+ 3.67 k . Cal$ 85. $If the standard enthalpy of sublimation (Δ_{sub} H^{\circ}) of solid CO_{2}, naphthalene, Li and Na are 25.2, 73.0, 162, 108 kJ mol respectively, the order of sublimation of these substances with temperature is .$ (1) $Na>Li> Naphthalene > Solid CO_{2}$ (2) $Solid CO_{2} > Na > Naphthalene > Li$ (3) $Solid CO_{2} > Naphthalene >Na>Li$ (4) $Li > Na > Naphthalene > Solid CO_{2} .$ 86. $A gas (Molar mass = 280 g m o l^{- 1}) was burnt in excess O_{2} in a constant volume calorimeter and during combustion the temperature of calorimeter increased from 298.0 K to 298.45 K. If the heat capacity of calorimeter is 2.5 kJ K^{- 1} and enthalpy of combustion of gas is 9 kJ m o l^{- 1} then amount of gas burnt is_______g. (Nearest Integer)$ 87. $The standard entropy change for the reaction 4Fe(s) + 3 O_{2} (g) \to 2 F e_{2} O_{3} (s) is -550 J K^{- 1} at 298 K. [Given : The standard enthalpy change for the reaction is -165 kJ mol"^{1}]. The temperature in K at which the reaction attains equilibrium is _________. (Nearest Integer)$ 88. $The heat of combustion of solid benzoic acid at constant volume is - 321.30 kJ at 27^{\circ} C . The heat of combustion at constant pressure is (- 321.30 - x R) kJ, the value of x is______$ 89. $One mole of He is mixed with 2 mole of Ne, both at the same temperature and pressure. Determine ΔS for the process in J/K in nearest possible integers, if the total volume remain constant. log 3 = 0.48 ; log 2 = 0.3$ 90. $For the reaction at 298 K, 2 A + B \to C . Δ H = 400 kJ mol^{- 1} and Δ S = 0.2 kJ mol^{- 1} K^{- 1} . The reaction will become spontaneous above K .$