Thermodynamics PYQs Set 2 (PDF)

Set 2 of 14 · Questions 31-60 of 393

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Mere Teacher · Previous Year Questions NEET Chemistry · Thermodynamics · Set 2 (Q31-60)
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31. $Which of the following endothermic processes are spontaneous?$ (1) $Melting of ice$ (2) $Evaporation of water$ (3) $Heat of combustion$ (4) $Both (a) and (b)$ 32. $At what temperature liquid water will be in equilibrium with water vapour? ∆ H_{v a p} = 40.73 k J m o l^{- 1}, ∆ S_{v a p} = 0.109 k J K^{- 1} m o l^{- 1}$ (1) $282.4 K$ (2) $373.6 K$ (3) $100 K$ (4) $400 K$ 33. $Pb O_{2} \to PbO; Δ G_{298} < 0 Sn O_{2} \to SnO; Δ G_{298} > 0 Most probable oxidation state of Pb and Sn will be$ (1) $P b^{4 +}, S n^{4 +}$ (2) $P b^{4 +}, S n^{2 +}$ (3) $P b^{2 +}, S n^{2 +}$ (4) $P b^{2 +}, S n^{4 +}$ 34. $Which among the following is a feature of adiabatic expansion?$ (1) $Δ V < 0$ (2) $Δ U < 0$ (3) $Δ U > 0$ (4) $Δ T = 0$ 35. $The criterion for a spontaneous process is$ (1) $Δ G > 0$ (2) $Δ G < 0$ (3) $Δ G = 0$ (4) $Δ S_{total} < 0$ 36. $Enthalpy of formation of CO (g), CO_{2} (g) are - 110, - 393 kJ mol^{- 1} respectively. The enthalpy of combustion of CO (in kJ mol^{- 1}) is$ (1) $-283.0$ (2) $-110.5$ (3) $504$ (4) $-221.2$ 37. $At 60^{\circ} C, dinitrogen tetroxide is 50 % dissociated. Find it's standard free energy change at this temperature and one atmosphere. [Given log 1.33 = 0.1239]$ (1) $- 650 J mol^{- 1}$ (2) $- 830 J mol^{- 1}$ (3) $- 790 J mol^{- 1}$ (4) $- 875 J mol^{- 1}$ 38. $Given (i) 2 F e_{2} O_{3} (s) \to 4Fe(s) + 3 O_{2} (g) ; D_{r} G° = + 1487.0 kJ m o l^{-1} (ii) 2CO(g) + O_{2} (g) \to 2 C O_{2} (g) ; D_{r} G° = -514.4 kJ m o l^{-1} Free energy change, D_{r} G° for the reaction 2 F e_{2} O_{3} (s) + 6CO(g) \to 4Fe(s) + 6 C O_{2} (g) will be$ (1) $-112.4 kJ m o l^{-1}$ (2) $-56.2 kJ m o l^{-1}$ (3) $-168.2 kJ m o l^{-1}$ (4) $-208.0 kJ m o l^{-1}$ 39. $The heat of atomisation of methane and ethane are ' x^{’} kJmol^{- 1} and ' y^{’} kJmol^{- 1} respectively. The longest wavelength (λ) of light capable of breaking the C - C bond can be expressed in SI unit as:$ (1) $\frac{N _{A} hc}{250 ( 4 y - 6 x )}$ (2) $\frac{hc}{1000} (\frac{y - 6 x}{4})^{- 1}$ (3) $\frac{N _{A} hc}{250 ( y - 6 x )}$ (4) $N_{A} hc (y - \frac{6 x}{4})^{- 1}$ 40. $The enthalpy of neutralisation of H C O_{3}^{-} (aq) with strong alkali is - 42 kJ/mole and enthalpy of neutralisation of strong acid with strong alkali is - 56 kJ/equiv. Therefore, enthalpy of dissociation of H C O_{3}^{-} (aq) is-$ (1) $- 98 kJ/mol$ (2) $98 kJ/mol$ (3) $14 kJ/mol$ (4) $24 kJ/mol$ 41. $The enthalpy of formation (Δ H_{f}) of methanol, formaldehyde and water are - 239, - 116 and - 286 kJ mol^{- 1} respectively. The enthalpy change for the oxidation of methanol to formaldehyde and water in kJ is$ (1) $-136$ (2) $-173$ (3) $163$ (4) $-163$ 42. $In the reaction: S + 3/2 O_{2} \to S O_{3} + 2 x kcal and S O_{2} + 1/2 O_{2} \to S O_{3} + y kcal, the heat of formation of S O_{2} is$ (1) $(2 x + y)$ (2) $(x - y)$ (3) $(x + y)$ (4) $(2 x - y)$ 43. $Two moles of an ideal gas are allowed to expand from a volume of 10 dm^{3} to 2 m^{3} at 300 K against a pressure of 101.325 kPa . Calculate the work done.$ (1) $- 201.6 kJ$ (2) $13.22 kJ$ (3) $- 810.6 J$ (4) $- 18.96 kJ$ 44. $C_{6} H_{12} O_{6} (S) + 6 O_{2} (g) \to 6 CO_{2} (g) + 6 H_{2} O (l) What is the Δ U for the same reaction at 300 K (kJ mol^{- 1}) ?$ (1) $-2802.49$ (2) $-2800.00$ (3) $-2814.94$ (4) $+2802.49$ 45. $The heat required to rise the temperature of 54 g of aluminium from 40^{\circ} C to 60^{\circ} C in J is (molar heat capacity of aluminium in this temperature range is 24 J mol^{- 1} K^{- 1}; atomic weight of Al is 27 )$ (1) $480$ (2) $800$ (3) $960$ (4) $1280$ 46. $For the chemical reaction X ⇌ Y the standard reaction Gibbs energy depends on temperature T (in K) as Δ_{r} G^{\circ} (in kJ mol^{- 1}) = 120 - \frac{3}{8} T The major component of the reaction mixture at T is :$ (1) $Y if T = 300 K$ (2) $Y if T = 280 K$ (3) $X if T = 350 K$ (4) $X if T = 315 K$ 47. $S (g) + \frac{3}{2} O_{2} (g) \to SO_{3} (g) + 2 x kcal SO_{2} (g) + \frac{1}{2} O_{2} (g) \to SO_{3} (g) + y kcal The heat of formation of SO_{2} (g) is given by:$ (1) $x + y kcal$ (2) $y - 2 x kcal$ (3) $\frac{2 x}{y} kcal$ (4) $2 x + y kcal$ 48. $The process is spontaneous at the given temperature, if$ (1) $Δ H is + ve and Δ S is -ve$ (2) $Δ H is -ve and Δ S is +ve$ (3) $Δ H is +ve and Δ S is +ve$ (4) $Δ H is +ve and Δ S is equal to zero.$ 49. $Enthalpy of vaporization of benzene is + 35.3 kJ mo l^{- 1} at its boiling point, 8 0^{\circ} C . The entropy change in the transition of the vapour to liquid at its boiling point (in J K^{- 1} mo l^{- 1}) is$ (1) $-441$ (2) $-100$ (3) $+441$ (4) $+100$ 50. $Based on the first law of thermodynamics, which one of the following is correct?$ (1) $For an isochoric process, Δ U = - q$ (2) $For an adiabatic process, Δ U = - w$ (3) $For an isothermal process, q = + w$ (4) $For a cyclic process, q = - w$ 51. $Which of the following does not follow first law of thermodynamics? (W = work; q = heat; Δ U = change in internal energy)$ (1) $W > 0; q > 0; Δ U < 0$ (2) $W = 0; q = 0; Δ U = 0$ (3) $W > 0; q = 0; Δ U > 0$ (4) $W < 0; q < 0; Δ U < 0$ 52. $If the enthalpy change for the transition of liquid water to steam is 30 kJmo l^{- 1} at 2 7^{o} C, the entropy change for the process would be$ (1) $10 J m o l^{- 1} K^{- 1}$ (2) $1.0 J m o l^{- 1} K^{- 1}$ (3) $0.1 J m o l^{- 1} K^{- 1}$ (4) $100 J m o l^{- 1} K^{- 1}$ 53. $In the reaction H_{2} O (l) \to H_{2} O (s) at 0^{\circ} C and 1 atm, the internal energy change is - 41 kJ / mol . What will be the value of molar enthalpy change?$ (1) $- 41 kJ / mol$ (2) $41 kJ / mol$ (3) $30 kJ / mol$ (4) $- 30 kJ / mol$ 54. $If one litre of an ideal gas at a pressure of 20 atm expands isothermally and reversibly to a final volume of ' X' L by absorbing 92.12 L . atm heat, ' X' (in L) is$ (1) $200$ (2) $20$ (3) $15$ (4) $100$ 55. $Identify the correct statement for change of Gibb’s energy for a system (Δ G_{system}) at constant temperature and pressure.$ (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) $If Δ G_{system} = 0, the system is still moving in a particular direction.$ 56. $The enthalpy and entropy change for the reaction: B r_{2 (l)} + C l_{2 (g)} \to 2 BrC l_{(g)} are 30 kJmo l^{- 1} and 105 J K^{- 1} mo l^{-} respectively. The temperature at which the reaction will be in equilibrium is$ (1) $300 K$ (2) $285.7 K$ (3) $273 K$ (4) $450 K$ 57. $In which state, matter have highest entropy$ (1) $Solid$ (2) $Liquid$ (3) $Gas$ (4) $Equal in all$ 58. $Work done by an ideal gas at a constant volume is\dots\dots\dots$ (1) $- \frac{Δ p}{p}$ (2) $- V Δ p$ (3) $0$ (4) $\frac{nR}{p}$ 59. $Let us consider a reversible reaction at temperature, T. In this reaction, both Δ H and Δ S were observed to have positive values. If the equilibrium temperature is Te, then the reaction becomes spontaneous at:$ (1) $Te > T$ (2) $T > Te$ (3) $T = Te$ (4) $Te = 5 T$ 60. $Lattice enthalpy and enthalpy of solution of NaCl are 788kJ mol^{- 1} and 4kJ mol^{- 1}, respectively. The hydration enthalpy of NaCl is$ (1) $784kJ mol^{- 1}$ (2) $- 780 kJ mol^{- 1}$ (3) $780kJ mol^{- 1}$ (4) $- 784 kJ mol^{- 1}$