Thermodynamics PYQs Set 5 (PDF)

Set 5 of 18 · Questions 121-150 of 511

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Mere Teacher · Previous Year Questions JEE Main Chemistry · Thermodynamics · Set 5 (Q121-150)
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121. $For a given reaction, Δ H = 35.5 kJmo l^{- 1} and Δ S = 83.6 J K^{- 1} mo l^{- 1} . The reaction is spontaneous at (Assume that Δ H and Δ S do not vary with temperature.)$ (1) $T > 425 K$ (2) $all temperatures$ (3) $T > 298 K$ (4) $T < 425 K$ 122. $The INCORRECT match in the following is :$ (1) $Δ G^{0} < 0, K > 1$ (2) $Δ G^{0} = 0, K = 1$ (3) $Δ G^{0} > 0, K < 1$ (4) $Δ G^{0} < 0, K < 1$ 123. $Calculate the difference between heat of combustion of carbon monoxide gas at constant pressure and at constant volume at 27^{\circ} C ? (R = 2 cal K^{- 1} mol^{- 1})$ (1) $54 cal$ (2) $- 600 cal$ (3) $- 300 cal$ (4) $27 cal$ 124. $In a closed insulated container, a liquid is stirred with a paddle to increase its temperature. In this process, which of the following is true$ (1) $∆ E = W = Q = 0$ (2) $∆ E \neq = 0, Q = W = 0$ (3) $∆ E = W \neq = 0, Q = 0$ (4) $∆ E = Q \neq = 0, W = 0$ 125. $Identify the equation in which change in enthalpy is equal to change in internal energy.$ (1) $2 H_{2} O_{2 (l)} \to 2 H_{2} O_{(l)} + O_{2 (g)}$ (2) $C_{(s)} + O_{2 (g)} \to CO_{2 (g)}$ (3) $PCl_{5 (g)} \to PCl_{3 (g)} + Cl_{2 (g)}$ (4) $N_{2 (g)} + 3 H_{2 (g)} \to 2 NH_{3 (g)}$ 126. $9.0 gm of H_{2} O is vaporised at 100^{\circ} C and 1 atm pressure. If the latent heat of vaporisation of water is x J / gm, then Δ S is given by$ (1) $\frac{x}{373}$ (2) $\frac{18 x}{100}$ (3) $\frac{18 x}{373}$ (4) $\frac{1}{2} \times \frac{18 x}{373}$ 127. $The first and second ionisation enthalpies of a metal are 496 and 4560 kJ moll, respectively. How many moles of HCl and H_{2} S O_{4}, respectively, will be needed to react completely with 1 mole of the metal hydroxide?$ (1) $l and 0.5$ (2) $2 and 0.5$ (3) $1 and 2$ (4) $1 and 1$ 128. $Which law of thermodyanamics help in calculating entropy at different temperatures$ (1) $First law$ (2) $Second law$ (3) $Third law$ (4) $Zeroth law$ 129. $An irreversible process occuring isothermally in an isolated system leads to$ (1) $Zero entropy$ (2) $An increase in the total entropy of the system$ (3) $A decrease in the total entropy of the system$ (4) $None of these$ 130. $The process with negative entropy change is:$ (1) $Sublimation of dry ice$ (2) $Dissolution of iodine in water$ (3) $Dissociation of C a S O_{4} (s) to CaO(s) and S O_{3} (g)$ (4) $Synthesis of ammonia from N_{2} and H_{2}$ 131. $The difference between Δ H and Δ U (Δ H - Δ U) whenthe combustion of one mole of heptane (I) is carried out at a temperature T, is equal to:$ (1) $- 4 RT$ (2) $- 3 RT$ (3) $4 RT$ (4) $3 RT$ 132. $According to first law of thermodynamics, which of the following options is correct?$ (1) $Encrgy can be created only.$ (2) $Energy can be destroyed only.$ (3) $Energy can neither be created nor be destroyed.$ (4) $None of these.$ 133. $The equilibrium constant of a reaction is 0.008 at 298 K . The standard free energy change of the reaction at the same temperature is$ (1) $+ 11.96 kJ$ (2) $- 11.96 kJ$ (3) $- 5.43 kJ$ (4) $- 8.46 kJ$ 134. $If 2.5 moles of an ideal gas at a certain temperature are allowed to expand isothermally and reversibly from an initial volume of 2 dm^{3} to 20 dm^{3}, the work done by the gas is - 16.5 kJ . The temperature (in K) of the gas is (Round off to the nearest value) (R = 8.314 J K^{- 1} mol^{- 1})$ (1) $445$ (2) $245$ (3) $345$ (4) $745$ 135. $The work done to contract a gas in a cylinder, is 462 joules. 128 joule energy is evolved in the process. What will be the internal energy change in the process$ (1) $+ 590 joules$ (2) $- 334 joules$ (3) $+ 334 joules$ (4) $- 590 joules$ 136. $During isothermal expansion of an ideal gas, its$ (1) $internal energy increases$ (2) $enthalpy decreases$ (3) $enthalpy remains unaffected$ (4) $enthalpy reduces to zero.$ 137. $One mole of an ideal gas at 300 K in thermal contact with surroundings expands isothermally from 1.0 L to 2.0 L against a constant pressure of 3.0 atm. In this process, the change in entropy of surroundings (D S_{s u r r}) in J K^{-1} is: (1 L atm = 101.3 J)$ (1) $5.763$ (2) $1.013$ (3) $-1.013$ (4) $-5.763$ 138. $An air bag on adiabatic expansion undergoes 5 % increase in its volume. The percentage change in pressure is (γ_{air} = 1.4)$ (1) $5$ (2) $6$ (3) $7$ (4) $9$ 139. $What is the amount of work done when 0.5 mole of methane, CH_{4 (g)}, is subjected to combustion at 300 K ? (given, R = 8.314 JK^{- 1} mol^{- 1})$ (1) $- 2494 J$ (2) $- 4988 J$ (3) $+ 4988 J$ (4) $+ 2494 J$ 140. $If 92 gNa reacts with water in open vessel at 300 K . What is the value of work done? [Assume ideal nature of the gaseous product]$ (1) $0.0$ (2) $- 4988.4 J$ (3) $- 2494.2 J$ (4) $- 9976.8 J$ 141. $Which among the following reactions exhibits Δ H = Δ U ?$ (1) $H_{2 (g)} + Br_{2 (g)} ⟶ 2 HBr_{(g)}$ (2) $2 CO_{(g)} + O_{2 (g)} ⟶ 2 CO_{2 (g)}$ (3) $PCl_{5 (g)} ⟶ PCl_{3 (g)} + Cl_{2 (g)}$ (4) $C_{(s)} + 2 H_{2} O_{(g)} ⟶ 2 H_{2 (g)} + CO_{2 (g)}$ 142. $If a refrigerator's door is opened, then we get$ (1) $Room heated$ (2) $Room cooled$ (3) $More amount of heat is passed out$ (4) $No effect on room$ 143. $Calculate the value of Δ G for following reaction at 300 K . (Δ H = 7 kJ, Δ S = 24.8 J K^{- 1}) H_{2} O_{(s)} ⟶ H_{2} O_{(l)}$ (1) $0.74 kJ mol^{- 1}$ (2) $- 0.82 kJ mol^{- 1}$ (3) $0.21 kJ mol^{- 1}$ (4) $- 0.44 k mol^{- 1}$ 144. $The true statement amongst the following is$ (1) $S is a function of temperature but Δ S is not a function of temperature$ (2) $both Δ S and S are functions of temperature$ (3) $both S and Δ S are not functions of temperature$ (4) $S is not a function of temperature but Δ S is a function of temperature.$ 145. $For the gas phase reaction, PC l_{5 (g)} ⇋ PC l_{3 (g)} + C l_{2 (g)} which of the following conditions are correct?$ (1) $Δ H < 0 and ΔS<0$ (2) $Δ H > 0 and Δ S < 0$ (3) $Δ H = 0 and ΔS<0$ (4) $ΔH>0 and Δ S > 0$ 146. $The enthalpy change for the adsorption process and micelle formation respectively are$ (1) $∆ H_{a d s} > 0 and ∆ H_{mi c} < 0$ (2) $∆ H_{a d s} > 0 and ∆ H_{mi c} > 0$ (3) $∆ H_{a d s} < 0 and ∆ H_{mi c} > 0$ (4) $∆ H_{a d s} < 0 and ∆ H_{mi c} < 0$ 147. $Which of the following relation is correct?$ (1) $dG = Vdp + SdT$ (2) $dG = Vdp - SdT$ (3) $Δ G = - RT ln (K)$ (4) $dU = pdV + TdS$ 148. $The internal energy change (in J) when 90g of water undergoes complete evaporation at 100°C is : (Given : ∆ H_{vap} for water at 373K = 41kJ/mol, R = 8.314 JK^{- 1} mol^{- 1})$ 149. $Standard entropies of X_{2}, Y_{2} and XY_{5} are 70,50 and 110 J K^{- 1} mol^{- 1} respectively. The temperature in Kelvin at which the reaction \frac{1}{2} X_{2} + \frac{5}{2} Y_{2} ⇌ XY_{5} Δ H^{Θ} = - 35 kJ mol^{- 1} will be at equilibrium is . (Nearest integer)$ 150. $The free energy change for a reaction is -213.3 kJ m o l^{-1} at 25ºC. If the enthalpy change of the reaction is -217.77 kJ m o l e^{-1} . Calculate the magnitude of entropy change for the reaction in Joule mole^{-1} .$