Thermodynamics PYQs Set 10 (PDF)

Set 10 of 14 · Questions 271-300 of 393

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Mere Teacher · Previous Year Questions NEET Chemistry · Thermodynamics · Set 10 (Q271-300)
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271. $For the chemical reaction X ⇌ Y, the standard reaction Gibbs energy depends on temperature T (in K) as DrG°(in kJ mol^{-1}) = 120 - \frac{3}{8} T . The major component of the reaction mixture at T is:$ (1) $Y is T = 280 K$ (2) $Y is T = 300 K$ (3) $X if T = 315 K$ (4) $X if T = 350 K$ 272. $Equal volumes of monoatomic and diatomic gases at same initial temperature and pressure are mixed. The ratio of specific heats (C_{p} / C_{v}) of the mixture will be$ (1) $1$ (2) $2$ (3) $1.67$ (4) $1.5$ 273. $What is the change in entropy when 2.5 mole of water is heated from 270C to 870C? Assume that the heat capacity is constant. (Cp,m (H2O) = 4.2 J/g-K ln (1.2) = 0.18)$ (1) $16.6 J/K$ (2) $9 J/K$ (3) $34.02 J/K$ (4) $1.89 J/K$ 274. $A gas undergoes change from state A to state B. In this process, the heat absorbed and work done by the gas is 5 J and 8 J, respectively. Now gas is brought back to A by another process during, which 3 J of heat is evolved. In this reverse process of B to A :$ (1) $10 J of the work will be done by the surrounding on gas.$ (2) $10 J of the work will be done by the gas.$ (3) $6 J of the work will be done by the surrounding on gas.$ (4) $6 J of the work will be done by the gas.$ 275. $The heat of atomixation of methane and ethane are 360 kJ/mol and 620 kJ/mol, respectively. The longest wavelength of light capable of breaking the C-C bond is : (A vogadro number = 6.02 \times 1 0^{23}, h = 6.62 \times 1 0^{-34} J s):$ (1) $2.48 \times 1 0^{3} nm$ (2) $1.49 \times 1 0^{3} nm$ (3) $2.49 \times 1 0^{4} nm$ (4) $2.48 \times 1 0^{4} nm$ 276. $The following graph indicates the system containing 1 mole of gas involving various steps. When it moves from z to x, the type of undergoing process is$ (1) $cyclic$ (2) $isothermal$ (3) $isochoric$ (4) $isobaric$ 277. $The standard entropies of C O_{2} (g), C (s) and O_{2} (g) are 213.5, 5.690 and 205 J K^{-1} respectively. The standard entropy of formation of C O_{2} (g) is$ (1) $1.86 J K^{-1}$ (2) $1.96 J K^{-1}$ (3) $2.81 J K^{-1}$ (4) $2.86 J K^{-1}$ 278. $The enthalpy of hydrogenation of cyclohexene is - 119.5 kJmo l^{- 1} . If resonance energy of benzene is - 150.4 kJmo l^{- 1}, its enthalpy of hydrogenation would be$ (1) $- 358.5 kJmo l^{- 1}$ (2) $- 508.9 kJmo l^{- 1}$ (3) $- 208.1 kJmo l^{- 1}$ (4) $- 269.9 kJmo l^{- 1}$ 279. $Gibbs energy vs T plot for the formation of oxides is given below. For the given diagram, the correct statement is-$ (1) $At 600°C, CO cannot reduce FeO$ (2) $At 600°C, CO can reduce ZnO$ (3) $At 600°C,C can reduce ZnO$ (4) $At 600°C,C can reduce FeO$ 280. $For which of the following processes, ΔS is negative ?$ (1) $C(diamond) \to C(graphite)$ (2) $N2(g, 1 atm) \to N2(g, 5 atm)$ (3) $N2(g, 273 K) \to N2(g, 300 K)$ (4) $H2(g) \to 2H(g)$ 281. $For a reaction, (4 M (s) + n O_{2} (g) \to 2 M_{2} O_{n} (s), the free energy change is plotted as a function of temperature. The temperature below which the oxide is stable could be inferred from the plot as the point at which$ (1) $the free energy change shows a change from negative to positive value$ (2) $the slope changes from positive to negative$ (3) $the slope changes from negative to positive$ (4) $the slope changes from positive to zero$ 282. $An ideal gas undergoes a cyclic process as shown in Figure. Δ U_{B C} = -5 kJ m o l^{-1}, q_{A B} = 2 kJ m o l^{-1} W_{A B} = -5 kJ m o l^{-1}, W_{C A} = 3 kJ m o l^{-1} Heat absorbed by the system during process CA is :$ (1) $- 5 kJ m o l^{-1}$ (2) $+ 5 kJ m o l^{-1}$ (3) $18 kJ m o l^{-1}$ (4) $- 18 kJ m o l^{-1}$ 283. $Ice and water are placed in a closed container at a pressure of 1 atm and temperature 273.15 K. If pressure of the system is increased 2 times, keeping temperature constant, then identify correct observation from following$ (1) $Volume of system increases .$ (2) $The solid phase (ice) disappears completely.$ (3) $Liquid phase disappears completely.$ (4) $The amount of ice decreases.$ 284. $If enthalpy of atomisation for B r_{2 (I)} is x kJ/mol and bond enthalpy for B r_{2} is y kJ/mol the relation between them :$ (1) $x> y$ (2) $x < y$ (3) $x = y$ (4) $Relation does not exist$ 285. $The hydration energies of K^{+} and Cl^{-} are - x and - y kJ / mol respectively. If the lattice energy of KCl is - z kJ / mol, then the heat of solution of KCl is:$ (1) $x + y + z$ (2) $z - (x + y)$ (3) $- z - (x + y)$ (4) $x - y - z$ 286. $For the equilibrium 2 H_{2} O ⇌ H_{3} O^{+} + O H^{-}, the value of DG° at 298 K is approximately :$ (1) $80 kJ m o l^{-1}$ (2) $-100 kJ m o l^{-1}$ (3) $-80 kJ m o l^{-1}$ (4) $100 kJ m o l^{-1}$ 287. $For an endothermic reaction, energy of activation is E_{a} and enthalpy of reaction is Δ H (both of these in kJ/mol). Minimum value of E_{a} will be$ (1) $less than Δ H$ (2) $equal to Δ H$ (3) $more than Δ H$ (4) $equal to zero$ 288. $Using the data provided, calculate the multiple bond energy (kJ m o l^{-1}) of a CºC bond C_{2} H_{2} . That energy is (take the bond energy of a C-H bond as 350 kJ m o l^{-1}) 2C(s) + H_{2} (g) ¾® C_{2} H_{2} (g) DH = 225 kJ m o l^{-1} 2C(s) ¾® 2C (g) DH = 1410 kJ m o l^{-1} H_{2} (g) ¾® 2H(g) DH = 330 kJ m o l^{-1}$ (1) $1165$ (2) $837$ (3) $865$ (4) $815$ 289. $Match List-I with List-II List-I (A) Spontaneous process (B) Process with Δ P = 0, Δ T=0 (C) Δ H_{r e a c tl o n} (D) Exothermic process List-II (I) Δ H < 0 (II) Δ G_{T . P} < 0 (III) Isothermal and isobaric process (IV) [Bond energies of molecules in reactants] [Bond energies of product molecules] Choose the correct answer from the options given below:$ (1) $(A) - (III), (B) - (II), (C) - (IV), (D) - (I)$ (2) $(A) - (II), (B) - (III), (C) - (IV), (D) - (I)$ (3) $(A) - (II), (B) - (III), (C) - (I), (D) - (IV)$ (4) $(A) - (II), (B) - (I), (C) - (III), (D) - (IV)$ 290. $(T = 300 K P = 15 bar 1 mole) (T = 300 K P = 10 bar 1 mole) (T = 300 K P = 5 bar 1 mole) Above shows a cyclic process. Calculate the total work done during one complete cycle..$ (1) $25/3 L bar$ (2) $- 25/3 L bar$ (3) $50/3 L bar$ (4) $- 50/3 L bar$ 291. $For a perfectly crystalline solid C_{p, m} = a T^{3} + b T, where a and b are constants. If C_{p, m} is 0.40 J / K m o l at 10 K and 0.92 J / K m o l at 20 K, then molar entropy at 20 K is :$ (1) $0.92 J / K m o l$ (2) $8.66 J / K m o l$ (3) $0.813 J / K m o l$ (4) $None of these$ 292. $Given: (i) C (g r a p hi t e) + O_{2} (g) \to C O_{2} (g); Δ_{r} H^{⊖} = x k J m o l^{- 1} (ii) C (g r a p hi t e) + \frac{1}{2} O_{2} (g) \to C O_{2} (g); Δ_{r} H^{⊖} = y k J m o l^{- 1} (iii) C O (g) + \frac{1}{2} O_{2} (g) \to C O_{2} (g); Δ_{r} H^{⊖} = z k J m o l^{- 1} Based on the above thermochemical equations, find out which one of the following algebraic relationship is correct?$ (1) $x = y - z$ (2) $y = 2z - x$ (3) $x = y + z$ (4) $z = x + y$ 293. $The effect of temperature on spontaneity of reactions are represented as: Δ H Δ S Temperature Spontaneity (A) + ◻ any T Non spontaneous (B) + + low T spontaneous (C) - - low T Non spontaneous (D) - + any T spontaneous$ (1) $(B) and (C) only$ (2) $(B) and (D) only$ (3) $(A) and (D) only$ (4) $(A) and (C) only$ 294. $Formation of a solution from two components can be considered as (i) Pure solvent \to separated solvent molecules, Δ H_{1} (ii) Pure solute \to separated solute molecules, Δ H_{2} (iii) Separated solvent and solute molecules \to solution, Δ H_{3} Solution so formed will be ideal if$ (1) $Δ H_{soln} = Δ H_{1} + Δ H_{2} + Δ H_{3}$ (2) $Δ H_{soln} = Δ H_{1} + Δ H_{2} - Δ H_{3}$ (3) $Δ H_{soln} = Δ H_{1} - Δ H_{2} - Δ H_{3}$ (4) $Δ H_{soln} = Δ H_{3} - Δ H_{1} - Δ H_{2}$ 295. $For the reaction, A (g) + B (g) \to C (g) + D (g), Δ H^{\circ} and Δ S^{\circ} are, respectively, - 29.8 kJ mo l^{- 1} and - 0.100 kJ K^{- 1} mo l^{- 1} at 298 K. The equilibrium constant for the reaction at 298 K is:$ (1) $1$ (2) $10$ (3) $1.0 \times 1 0^{-10}$ (4) $1.0 \times 1 0^{10}$ 296. $The incorrect expression among the following is:$ (1) $\frac{Δ G _{sy s t e m}}{Δ S _{t o t a l}} = - T$ (2) $In isothermal process, w_{r e v er s ib l e} = - n R T ℓ n \frac{V _{f}}{V _{i}}$ (3) $ln K = \frac{Δ H ^{0} - T Δ S ^{0}}{R T}$ (4) $K = e^{- Δ G^{0} / R T}$ 297. $Find the heat required to make water of 3 0^{\circ} C from 10 g of ice at 0. 0^{\circ} C . (Enthalpy of fusion of ice = 333.55 J g^{- 1}, C_{P} of water = 4.18 J g^{- 1} K^{- 1})$ (1) $4.0 kJ$ (2) $5.0 kJ$ (3) $3.59 kJ$ (4) $4.59 kJ$ 298. $Match the LIST-I with LIST-II List-I (Thermodynamic Process) (A) Work done in reversible, isothermal expansion of 2 mol ideal gas from 2 dm^{3} to 20 dm^{3} at 300 K (B) Work done in irreversible isothermal expansion of 1 mol ideal gas from 1 m^{3} to 3 m^{3} at 300 K against constant pressure 3 kPa (C) Change in internal energy for adiabatic expansion of 1 mol ideal gas, Δ T = 320 K, C_{V} = \frac{3}{2} R (D) Change in enthalpy at constant pressure of 1 mol ideal gas, Δ T = 337 K, C_{p} = \frac{5}{2} R List-II (Magnitude in kJ) (I) 4 (II) 11.5 (III) 6 (IV) 7 Choose the correct answer from the options given below:$ (1) $A-II, B-III, C-I, D-IV$ (2) $A-III, B-II, C-IV, D-I$ (3) $A-II, B-I, C-III, D-IV$ (4) $A-I, B-II, C-III, D-IV$ 299. $Given below are two statements: Statement I: When a system containing ice in equilibrium with water (liquid) is heated, heat is absorbed by the system and there is no change in the temperature of the system until whole ice gets melted. Statement II: At melting point of ice, there is absorption of heat in order to overcome intermolecular forces of attraction within the molecules of water in ice and kinetic energy of molecules is not increased at melting point. In the light of the above statements, choose the correct answer from the options given below$ (1) $Both Statement I and Statement II are false$ (2) $Statement I is true but Statement II is false$ (3) $Both Statement I and Statement II are true$ (4) $Statement I is false but Statement II is true$ 300. $Calculate Δ_{r} H (kJ mol^{- 1}) of the following reaction C_{2} H_{5} OH (I) + 7/2 O_{2} (g) \to 2 CO_{2} (g) + 3 H_{2} O (I) Molecule Δ_{f} H^{0} (kJ mol^{- 1}) C_{2} H_{5} OH (I) -280 CO_{2} (g) -400 H_{2} O (l) -290$ (1) $-1950$ (2) $-1100$ (3) $-1390$ (4) $-700$