Thermodynamics PYQs Set 10 (PDF)

Set 10 of 18 · Questions 271-300 of 511

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Mere Teacher · Previous Year Questions JEE Main Chemistry · Thermodynamics · Set 10 (Q271-300)
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271. $Enthalpy of C H_{4} + \frac{1}{2} O_{2} \to C H_{3} OH is negative. If enthalpy of combustion of C H_{4} and C H_{3} OH are x and y respectively. Then which relation is correct?$ (1) $x > y$ (2) $x < y$ (3) $x = y$ (4) $x^{3} y$ 272. $The standard enthalpy of atomization of ethane according to the equation C_{2} H_{6} (g) \to 2 C (g) + 6 H (g) is 622 kJ mol^{- 1} . If standard mean C - H bond dissociation enthalpy is 90 kJ mol^{- 1}, the standard mean dissociation enthalpy of C-C bond (in kJ mol^{- 1}) is$ (1) $540$ (2) $90$ (3) $85$ (4) $82$ 273. $The work done during combustion of 9 \times 10^{- 2} kg of ethane, C_{2} H_{6 (g)} at 300 K is (Given, R = 8.314 J deg^{- 1} mol^{- 1}, atomic mass C = 12, H = I)$ (1) $6.236 kJ$ (2) $- 6.236 kJ$ (3) $18.71 kJ$ (4) $- 18.71 kJ$ 274. $The entropy change involved in the isothermal reversible expansion of 2 moles of an ideal gas from a volume of 10 d m^{3} to a volume of 100 d m^{3} at 2 7^{0} C is:$ (1) $38.3 J m o l^{-1} K^{-1}$ (2) $35.8 J m o l^{-1} K^{-1}$ (3) $32.3 J m o l^{-1} K^{-1}$ (4) $42.3 J m o l^{-1} K^{-1}$ 275. $The enthalpy of vapourisation of a liquid is 30 kJ m o l^{-1} and entropy of vapourisation is 75 m o l^{-1} K. The boiling point of the liquid at 1 atm is$ (1) $250 K$ (2) $400 K$ (3) $450 K$ (4) $600 K$ 276. $The correct statement amongst the following is:$ (1) $The standard state of a pure gas is the pure gas at a pressure of 1 bar and temperature 273 K.$ (2) $Δ_{f} H_{500}^{\circ} is zero for O_{2} (g) .$ (3) $Δ_{f} H_{298}^{\circ} is zero for O (g) .$ (4) $The term 'standard state' implies that the temperature is 0^{\circ} C .$ 277. $The absolute enthalpy of neutralisation of the reaction: Mg O_{(s)} + 2 HC l_{(aq)} \to MgC l_{2 (aq)} + H_{2} O_{(l)} will be$ (1) $- 57.33 kJmo l^{- 1}$ (2) $greater than - 57.33 kJmo l^{- 1}$ (3) $less than - 57.33 kJmo l^{- 1}$ (4) $57.33 kJmo l^{- 1}$ 278. $Which of the following mixing of 1 M base and 1 M acid leads to the largest increase in temperature?$ (1) $30 mLCH_{3} COOH and 30 mL NaOH$ (2) $45 mLCH_{3} COOH and 25 mLNaOH$ (3) $30 mL HCl and 30 mL NaOH$ (4) $50 mL HCl and 20 mL NaOH$ 279. $For one mole of an ideal gas, which of these statements must be true? (A) U and H each depends only on temperature (B) Compressibility factor z is not equal to 1 (C) C_{P, m} - C_{v, m} = R (D) dU = C_{v} dT for any process$ (1) $(A) and (C)$ (2) $(A), (C) and (D)$ (3) $(B), (C) and (D)$ (4) $(C) and (D)$ 280. $In a closed insulated container a liquid is stirred with a paddle to increase the temperature which of the following is true?$ (1) $Δ E = W \neq = 0, q = 0$ (2) $Δ E = W = q \neq = 0$ (3) $Δ E = 0, W = q \neq = 0$ (4) $W = 0, Δ E = q \neq = 0.$ 281. $Standard entropy of X_{2}, Y_{2} and XY_{3} are 60, 40 and 50 J K^{-1} m o l^{-1}, respectively. For the reaction, \frac{1}{2} X_{2} + \frac{3}{2} Y_{2} \to XY_{3} ∆ H = - 30 kJ. To be at equilibrium the temperature will be:$ (1) $500 K$ (2) $750 K$ (3) $1000 K$ (4) $1250 K$ 282. $If standard molar enthalpy change and standard molar internal energy change measured in bomb calorimeter are equal, which one of the following statements is correct?$ (1) $Δ n > 0, with increase in pressure$ (2) $Δ n > 0, with decrease in pressure$ (3) $Δ n < 0, with increase in pressure$ (4) $Δ n = 0, at constant pressure$ 283. $Which of the following are not state functions? (I) q + w (II) q (III) w (IV) H - TS$ (1) $(I), (II) and (III)$ (2) $(II) and (III)$ (3) $(I) and (IV)$ (4) $(II), (III) and (IV)$ 284. $At 298.2 the relationship between enthalpy of bond dissociation (in k J m o l^{- 1}) for hydrogen (_{H}^{E}) and its isotope, deuterium (_{D}^{E}), is best described by:$ (1) $E_{H} = \frac{1}{2} E_{D}$ (2) $E_{H} = E_{D}$ (3) $E_{H} = E_{D} - 7.5$ (4) $E_{H} = 2 E_{D}$ 285. $Which of the following is not an intensive property?$ (1) $Entropy$ (2) $Melting point$ (3) $Specific gravity$ (4) $Refractive index$ 286. $Which one of the following process is non-spontaneous?$ (1) $Dissolution of C u S O_{4} in water$ (2) $Reaction between H_{2} and O_{2} to form water$ (3) $Water flowing down hill$ (4) $Flow of electric current from low potential to high potential$ 287. $If the enthalpy and entropy change for a reaction at 298 K are - 145 kJ mol^{- 1} and - 650 J K^{- 1} mol^{- 1} respectively, which one of the following statements is correct?$ (1) $Δ G = - 50 kJ mol^{- 1}, the reaction is spontaneous$ (2) $Δ G = - 48.7 kJ mol^{- 1}, the reaction is nonspontaneous$ (3) $Δ G = + 50 kJ mol^{- 1}, the reaction is spontaneous$ (4) $Δ G = 48.7 kJ mol^{- 1}, the reaction is non-spontaneous$ 288. $If Δ G and Δ S for the reaction A (g) \to B (g) + 2 C (g) at 2000 K are - 40 kJ mol^{- 1} and 0.22 kJ K^{- 1} mol^{- 1} respectively, the change in internal energy for the same reaction approximately (in kJ mol^{- 1}) is$ (1) $366.7$ (2) $-33736$ (3) $433.3$ (4) $-433.3$ 289. $Given Δ H_{r}^{\circ} for CO_{2} (g), CO (g) and H_{2} O (g) are -393.5, -110.5 and - 241.8 kJ mol^{- 1}, respectively. The Δ H_{r}^{\circ} (in kJ mol^{- 1}) for the reaction CO_{2} (g) + H_{2} (g) ⟶ CO (g) + H_{2} O (g) is$ (1) $524.1$ (2) $-262.5$ (3) $-41.7$ (4) $41.2$ 290. $Which of the following is the least random state of water$ (1) $Ice$ (2) $Liquid water$ (3) $Steam$ (4) $All present same random state$ 291. $In which of the following conditions a chemical reaction can not occur$ (1) $∆ H and ∆ S increase and T ∆ S > ∆ H$ (2) $∆ H and ∆ S decrease and ∆ H > T ∆ S$ (3) $∆ H increases and ∆ S decreases$ (4) $∆ H decreases and ∆ S increases$ 292. $If for a certain reaction Δ_{r} H is 30 kJ mol^{- 1} at 450 K , the value of Δ_{r} S (in JK^{- 1} mol^{- 1}) for which the same reaction will be spontaneous at the same temperature is$ (1) $-33$ (2) $33$ (3) $-70$ (4) $70$ 293. $Combustion of sucrose is used by aerobic organisms for providing energy for the life sustaining processes. If all the capturing of energy from the reaction is done through electrical process (non P-V work) then calculate maximum available energy which can be captured by combustion of 34.2 g of sucrose Given : ∆ H_{co mb u s t i o n} (sucrose) = - 6000 kJ m o l^{-1} ∆ S_{co mb u s t i o n} = 180 J/K - mol and body temperature is 300 K$ (1) $600 kJ$ (2) $594.6 KJ$ (3) $5.4 kJ$ (4) $605.4 kJ$ 294. $For a chemical reaction A + B ⇌ C + D (∆_{r} H^{⊖} = 80 kJmo l^{- 1}) the entropy change ∆_{r} S^{⊖} depends on thetemperature T (in K) as ∆_{r} S^{⊖} = 2 T (J K^{- 1} mo l^{- 1}) Minimum temperature at which it will become spontaneous is ____ K.$ 295. $For the formation of C (g) at 300 K. A (g) + 3 B (g) \to 2C (g) Calculate the magnitude of ΔGº (Kcal) if given data : A B C ΔHfº (Kcal mol^{- 1}) 00 -10 ΔSfº(Cal K^{-1} mol^{- 1}) 403045$ 296. $If three moles of an ideal gas at 300 K expand isotherrnally from 30 dm^{3} to 45 dm^{3} against a constant opposing pressure of 80 kPa, then the amount of heat transferred is_______ J.$ 297. $A(g) 2B(g) + C(g)For the given reaction, if the initial pressure is 450 mmHg and the pressure at time t is720 mmHg at a constant temperature T and constant volume V. The fraction of A(g) decomposed under these conditions is x x 10-1. The value of x is (nearest integer)$ 298. $Enthalpies of formation of C C l_{4} (g), H_{2} O(g), C O_{2} (g)and HCl(g) are -105, -242, -394 and -92 kJ m o l^{- l} respectively. The magnitude of enthalpy of the reaction given below is______ kJ m o l^{- 3} (nearest integer) C C 1_{4} (g) + 2 H_{2} O(g) \to C O_{2} (g) + 4HCl(g)$ 299. $Consider the following data : Heat of formation of CO_{2} (g) = - 393.5 kJ mol^{- 1} Heat of formation of H_{2} O (l) = - 286.0 kJ mol^{- 1} Heat of combustion of benzene = - 3267.0 kJ mol^{- 1} The heat of formation of benzene is kJmol^{- 1} . (Nearest integer)$ 300. $1 mole of ideal gas is allowed to expand reversibly and adiabatically from a temperature of 27°C. The work done is 3 kJ m o l^{- 1} . The final temperature of the gas is _______K (Nearest integer). Given C_{v} =20 J m o l^{- 1} K^{- 1},$