Thermodynamics PYQs Set 12 (PDF)

Set 12 of 18 · Questions 331-360 of 511

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Mere Teacher · Previous Year Questions JEE Main Chemistry · Thermodynamics · Set 12 (Q331-360)
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331. $For the chemical reaction X ⇌ Y, the standard reaction Gibbs energy depends on temperature T (in K) as DrG°(in kJ mol^{-1}) = 120 - \frac{3}{8} T . The major component of the reaction mixture at T is:$ (1) $Y is T = 280 K$ (2) $Y is T = 300 K$ (3) $X if T = 315 K$ (4) $X if T = 350 K$ 332. $Equal volumes of monoatomic and diatomic gases at same initial temperature and pressure are mixed. The ratio of specific heats (C_{p} / C_{v}) of the mixture will be$ (1) $1$ (2) $2$ (3) $1.67$ (4) $1.5$ 333. $What is the change in entropy when 2.5 mole of water is heated from 270C to 870C? Assume that the heat capacity is constant. (Cp,m (H2O) = 4.2 J/g-K ln (1.2) = 0.18)$ (1) $16.6 J/K$ (2) $9 J/K$ (3) $34.02 J/K$ (4) $1.89 J/K$ 334. $A gas undergoes change from state A to state B. In this process, the heat absorbed and work done by the gas is 5 J and 8 J, respectively. Now gas is brought back to A by another process during, which 3 J of heat is evolved. In this reverse process of B to A :$ (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) $6 J of the work will be done by the gas.$ 335. $The heat of atomixation of methane and ethane are 360 kJ/mol and 620 kJ/mol, respectively. The longest wavelength of light capable of breaking the C-C bond is : (A vogadro number = 6.02 \times 1 0^{23}, h = 6.62 \times 1 0^{-34} J s):$ (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) $2.48 \times 1 0^{4} nm$ 336. $The following graph indicates the system containing 1 mole of gas involving various steps. When it moves from z to x, the type of undergoing process is$ (1) $cyclic$ (2) $isothermal$ (3) $isochoric$ (4) $isobaric$ 337. $The standard entropies of C O_{2} (g), C (s) and O_{2} (g) are 213.5, 5.690 and 205 J K^{-1} respectively. The standard entropy of formation of C O_{2} (g) is$ (1) $1.86 J K^{-1}$ (2) $1.96 J K^{-1}$ (3) $2.81 J K^{-1}$ (4) $2.86 J K^{-1}$ 338. $The enthalpy of hydrogenation of cyclohexene is - 119.5 kJmo l^{- 1} . If resonance energy of benzene is - 150.4 kJmo l^{- 1}, its enthalpy of hydrogenation would be$ (1) $- 358.5 kJmo l^{- 1}$ (2) $- 508.9 kJmo l^{- 1}$ (3) $- 208.1 kJmo l^{- 1}$ (4) $- 269.9 kJmo l^{- 1}$ 339. $One mole of an ideal diatomic gas (C_{v} = 5cal) was transformed from initial 25°C and 1L to the state when temperature is 100°C and volume 10L. Then for this process (R = 2 Calories/mol/K) (take calories as unit of energy and kelvin for temp )$ (1) $ΔH = 525$ (2) $ΔS = 5 ln \frac{373}{298} + 2 ln 10$ (3) $ΔE = 525$ (4) $ΔG of the process can not be calculated using given information$ 340. $Gibbs energy vs T plot for the formation of oxides is given below. For the given diagram, the correct statement is-$ (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) $At 600°C,C can reduce FeO$ 341. $For which of the following processes, ΔS is negative ?$ (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) $H2(g) \to 2H(g)$ 342. $For a reaction, (4 M (s) + n O_{2} (g) \to 2 M_{2} O_{n} (s), the free energy change is plotted as a function of temperature. The temperature below which the oxide is stable could be inferred from the plot as the point at which$ (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) $the slope changes from positive to zero$ 343. $An ideal gas undergoes a cyclic process as shown in Figure. Δ U_{B C} = -5 kJ m o l^{-1}, q_{A B} = 2 kJ m o l^{-1} W_{A B} = -5 kJ m o l^{-1}, W_{C A} = 3 kJ m o l^{-1} Heat absorbed by the system during process CA is :$ (1) $- 5 kJ m o l^{-1}$ (2) $+ 5 kJ m o l^{-1}$ (3) $18 kJ m o l^{-1}$ (4) $- 18 kJ m o l^{-1}$ 344. $For an ideal gas, consider only P-V work in going from an initial state X to the final state Z. The final state Z can be reached by either of the two paths shown in the figure. Which of the following choice(s) is (are) correct? [take ΔS as change in entropy and w as work done].$ (1) $ΔSx\toz = ΔSx\toy + ΔSy\toz$ (2) $wx\toz = wx\toy + wy\toz$ (3) $wx\toy\toz = wx\toy$ (4) $ΔSx\toy\toz = ΔSx\toy$ 345. $Ice and water are placed in a closed container at a pressure of 1 atm and temperature 273.15 K. If pressure of the system is increased 2 times, keeping temperature constant, then identify correct observation from following$ (1) $Volume of system increases .$ (2) $The solid phase (ice) disappears completely.$ (3) $Liquid phase disappears completely.$ (4) $The amount of ice decreases.$ 346. $If enthalpy of atomisation for B r_{2 (I)} is x kJ/mol and bond enthalpy for B r_{2} is y kJ/mol the relation between them :$ (1) $x> y$ (2) $x < y$ (3) $x = y$ (4) $Relation does not exist$ 347. $The hydration energies of K^{+} and Cl^{-} are - x and - y kJ / mol respectively. If the lattice energy of KCl is - z kJ / mol, then the heat of solution of KCl is:$ (1) $x + y + z$ (2) $z - (x + y)$ (3) $- z - (x + y)$ (4) $x - y - z$ 348. $For the equilibrium 2 H_{2} O ⇌ H_{3} O^{+} + O H^{-}, the value of DG° at 298 K is approximately :$ (1) $80 kJ m o l^{-1}$ (2) $-100 kJ m o l^{-1}$ (3) $-80 kJ m o l^{-1}$ (4) $100 kJ m o l^{-1}$ 349. $28.0 L of C O_{2} is produced on complete combustion of 16.8 L gaseous mixture of ethene and methane at 25°C and 1 atm. Heat evolved during the combustion process is________kJ. Given : ∆ H_{C} (C H_{4}) = -900 kJ m o l^{- 1} ∆ H_{C} (C_{2} H_{4}) = -1400 kJ m o l^{- 1}$ 350. $F e O_{4}^{2 -} + 2.2 V F e^{3 +} + 0.70 V F e^{2 +} - 0.45 V F e^{0} E_{Fe O_{4}^{2 -} / F e^{2 +}}^{θ} is x \times 1 0^{- 3} V . The value of x is _____$ 351. $One mole of an ideal gas at 350 K is in a 2.0 L vessel of thermally conducting walls, which are in contact with the surroundings. It undergoes isothermal reversible expansion from 2. 0 L to 3.0 L against a constant pressure of 4 atm. The change in entropy of the surroundings (∆ S) is_____J K^{- 1} (Nearest integer) Given: R = 8. 314 J K^{- 1} m o l^{- 1} .$ 352. $A2 + B2 \to 2 AB. Δ H_{f} = -200 kJ mol-1 AB, A2 and B2 are diatomic molecules. If the bond enthalpies of A2, B2 and AB are in the ratio l: 0. 5 : 1, then the bond enthalpy of A2 is_________kJ mol-1 (Nearest integer)$ 353. $A perfect gas (0.1 mol) having C_{v} = 1.50 R (independent of temperature) undergoes the above transformation from point 1 to point 4. If each step is reversible, the total work done (w) while going from point 1 to point 4 is (-) J (nearest integer) [Given: R = 0.082 L atm K^{- 1} mol^{- 1}]$ 354. $One mole of an ideal gas is taken from a and b along two paths denoted by the solid and the dashed lines as shown in the graph below. If the work done along the solid line path is w_{s} and that along the dotted line path is w_{d}, then the integer closest to the ratio w_{d} / w_{s} is : A$ 355. $2 O_{3} (g) ⇌ 3 O_{2} (g) At 300 K, ozone is fifty percent dissociated. The standard free energy change at this temperature and 1 atm pressure is (-)_J mol-1 (Nearest integer) [Given: In 1.35 = 0.3 and R = 8.3 J K^{- 1} mol-1]$ 356. $200 mL of 0.2 M HCl is mixed with 300 mL of 0.1 M NaOH. The molar heat of neutralization of this reaction is -57.1 kJ. The increase in temperature in \circC of the system on mixing is x \times 1 0^{- 2} . The value of x is ____. (Nearest integer)[Given : Specific heat of water = 4.18 J g^{- 1} K^{- 1} Density of water = 1.00 g c m^{- 3}] (Assume no volume change on mixing)$ 357. $For a given chemical reaction A \to B at 300K the free energy change is - 49.4 k J m o l^{- 1} and the enthalpy of reaction 51.4 k J m o l^{- 1} is The entropy change of the reaction is ___J K^{- 1} m o l^{- 1}$ 358. $2.4 g coal is burnt in a bomb calorimeter in excess of oxygen at 298 K and 1 atm pressure. The temperature of the calorimeter rises from 298 K to 300 K. The enthalpy change during the combustion of coal is - x kJ m o l^{- 1} . The value of x is___________. (Nearest Integer)(Given : Heat capacity of bomb calorimeter 20.0 kJ K^{- 1} . Assume coal to be pure carbon)$ 359. $An average person needs about 10000kJ energy per day. The amount of glucose (molar mass = 180.0 g m o l^{- 1}) needed to meet this energy requirement is ___ g. (Use : Δ_{C} H (glucose) = - 2700 kJ mol^{- 1})$ 360. $Solid fuel used in rocket is a mixture of Fe2 63 and Al (in ratio 1 : 2). The heat evolved (kJ) per gram of the mixture is_____(Nearest integer) Given Δ H_{f}^{0} (A 1_{2} O_{3})= -1700 kJ mol-1 Δ H_{f}^{0} (F e_{2} O_{3})= -840 kJ mol-1 Molar mass of Fe, AI and O are 56, 27 and 16 g mol-1 respectively$