Thermodynamics PYQs Set 6 (PDF)

Set 6 of 18 · Questions 151-180 of 511

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Mere Teacher · Previous Year Questions JEE Main Chemistry · Thermodynamics · Set 6 (Q151-180)
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151. $A cup of water at 5^{\circ} C (system) is placed in a microwave oven and the oven is turned on for one minute during which the water begins to boil. Which of the following option is true ?$ (1) $q = + ve, w = 0, Δ U = - ve$ (2) $q = + ve, w = - ve, Δ U = - ve$ (3) $q = - ve, w = - ve, Δ U = - ve$ (4) $q = + ve, w = - ve, Δ U = + ve$ 152. $One mole of an ideal gas expands isothermally and reversibly from 10 dm^{3} to 20 dm^{3} at 300 K. Δ U, q and work done in the process respectively are Given: R = 8.3 J K^{- 1} mol^{- 1} ln 10 = 2.3 log 2 = 0.30 log 3 = 0.48$ (1) $0, 21.84 kJ, - 1.726 J$ (2) $0, 21.84 kJ, 21.84 kJ$ (3) $0, 1.718 kJ, - 1.718 kJ$ (4) $0, - 17.18 kJ, 1.718 J$ 153. $11.0 L of an ideal gas at a constant external pressure of 5 atm is compressed isothermally to a final volume of one liter. The heat absorbed and work done respectively, during this compression (in L atm) are$ (1) $- 50, - 50$ (2) $50, - 50$ (3) $- 50, 50$ (4) $50,50$ 154. $20.0 dm^{3} of an ideal gas ' X ' at 600 K and 0.5 MPa undergoes isothermal reversible expansion until pressure of the gas is 0.2 MPa. Which of the following option is correct? (Given: log 2 = 0.3010 and log 5 = 0.6989)$ (1) $w = - 9.1 kJ, Δ U = 0, Δ H = 0, q = 9.1 kJ$ (2) $w = + 4.1 kJ, Δ U = 0, Δ H = 0; q = - 4.1 kJ$ (3) $w = 9.1 J, Δ U = 9.1 J, Δ H = 0; q = 0$ (4) $w = - 3.9 kJ, Δ U = 0, Δ H = 0; q = 3.9 kJ$ 155. $The increase in entropy in JK^{- 1} of a substance when it absorbs 1 kJ of heat energy at 3 K is$ (1) $3.33$ (2) $333.3$ (3) $0.333$ (4) $0.0333$ 156. $A system absorb 600J of heat and work equivalent to 300J on its surroundings. The change in internal energy is$ (1) $300 J$ (2) $400 J$ (3) $500 J$ (4) $600 J$ 157. $Standard entropies of X_{2}, Y_{2} and X Y_{3} are 60, 40 and 50 J K^{- 1} mo l^{- 1} respectively. For the reaction 1/2 X_{2} + 3/2 Y_{2} ⇋ X Y_{3}, Δ H = - 30 kJ, to be at equilibrium, the temperature should be$ (1) $750 K$ (2) $1000 K$ (3) $1250 K$ (4) $500 K$ 158. $For chemical reactions, the calculation of change in entropy is normally done$ (1) $At constant pressure$ (2) $At constant temperature$ (3) $At constant temperature and pressure both$ (4) $At constant volume$ 159. $The work done when 2 moles of an ideal gas expands reversibly and isothermally from a volume of 1 L to 10 L at 300 K is (R = 0.0083 kJ K mol^{- 1})$ (1) $0.115 kJ$ (2) $58.5 kJ$ (3) $11.5 kJ$ (4) $5.8 kJ$ 160. $Assume each reaction is carried out in an open container. For which reaction will Δ H = Δ E ?$ (1) $2 C O_{(g)} + O_{2 (g)} \to 2 C O_{2 (g)}$ (2) $H_{2 (g)} + B r_{2 (g)} \to 2 HB r_{(g)}$ (3) $C_{(s)} + 2 H_{2} O_{(g)} \to 2 H_{2 (g)} + C O_{2 (g)}$ (4) $PC l_{5 (g)} \to PC l_{3 (g)} + C l_{2 (g)}$ 161. $Which among the following equations represents the first law of thermodynamics under isobaric conditions?$ (1) $Δ U = q_{p} - p_{ext} \cdot Δ V$ (2) $q_{v} = Δ U$ (3) $Δ U = w$ (4) $w = - q$ 162. $Calculate the energy required to convert all atoms in 4.8 g of Mg to Mg^{2 +} in the vapour state. IE_{1} and IE_{2} of Mg are 740 kJ / mol and 1450 kJ / mol respectively.$ (1) $+ 740 kJ / mol$ (2) $- 740 kJ / mol$ (3) $- 1450 kJ / mol$ (4) $+ 438 kJ / mol$ 163. $A gas expands from a volume of 1 m^{3} to a volume of 2 m^{3} against an external pressure of 10^{5} N m^{- 2} . The work done by the gas will be$ (1) $10^{5} kJ$ (2) $10^{2} kJ$ (3) $10^{2} J$ (4) $10^{3} J$ 164. $Which of the follwing is incorrect regarding Gibbs free energy$ (1) $it is a state function$ (2) $it is extensive property$ (3) $it is macroscopic property$ (4) $it is intensive property$ 165. $For a reaction to be spontaneous at all temperatures$ (1) $Δ G and Δ H should be negative$ (2) $Δ G and Δ H should be positive$ (3) $Δ G = Δ S = 0$ (4) $Δ H < Δ G .$ 166. $The combustion of benzene (I) gives C O_{2} (g) and H_{2} O(l). Given that heat of combustion of benzene at constant volume is -3263.9 kJ m o l^{-1} at 25ºC; heat of combustion (in kJ m o l^{-1}) of benzene at constant pressure will be: (R = 8.314 J K^{-1} m o l^{-1})$ (1) $3260$ (2) $-3267.6$ (3) $4152.6$ (4) $-452.46$ 167. $An isolated system comprises the liquid in equilibrium with vapours. At this stage the molar entropy of the vapour is:$ (1) $Less than that of liquid$ (2) $more than that of liquid$ (3) $Equal to zero$ (4) $Equal to that of liquid$ 168. $In the reaction, S + \frac{3}{2} O_{2} ⟶ SO_{3} + 2 x kJ and SO_{2} + \frac{1}{2} O_{2} ⟶ SO_{3} + y kJ heat of formation of SO_{2} is$ (1) $x - y$ (2) $2 x + y$ (3) $x + y$ (4) $y - 2 x$ 169. $An ideal gas is allowed to expand from 1 L to 10 L against a constant external pressure of 1 bar. The work done in kJ is:$ (1) $- 9.0$ (2) $+ 10.0$ (3) $- 0.9$ (4) $- 2.0$ 170. $A process will be spontaneous at all temperatures if:$ (1) $Δ H < 0 and Δ S < 0$ (2) $Δ H > 0 and Δ S < 0$ (3) $Δ H < 0 and Δ S > 0$ (4) $Δ H > 0 and Δ S > 0$ 171. $Consider the reversible isothermal expansion of an ideal gas in a closed system at two different temperatures T_{1} and T_{2} (T_{1} < T_{2}). The correct graphical depiction of the dependence of work done (w) on the final volume (V) is:$ (1) (2) (3) (4) 172. $Match List - I with List - II. List - I (Partial Derivatives) (A) (\frac{\partial G}{\partial T})_{P} (B) (\frac{\partial H}{\partial T})_{P} (C) (\frac{\partial G}{\partial P})_{T} (D) (\frac{\partial U}{\partial T})_{V} List - II (Thermodynamic Quantity) (I) Cp (II) - S (III) Cv (IV) V Choose the correct answer from the options given below:$ (1) $(A)-(II), (B)-(I), (C)-(III), (D)-(IV)$ (2) $(A)-(I), (B)-(II), (C)-(IV), (D)-(III)$ (3) $(A)-(II), (B)-(I), (C)-(IV), (D)-(III)$ (4) $(A)-(II), (B)-(III), (C)-(I), (D)-(IV)$ 173. $The reaction in which Δ H > Δ U is$ (1) $N_{2 (g)} + O_{2 (g)} \to 2 NO_{(g)}$ (2) $CaCO_{3 (s)} \to CaO_{(s)} + CO_{2 (g)}$ (3) $N_{2 (g)} + 3 H_{2 (g)} \to 2 NH_{3 (g)}$ (4) $CH_{4 (g)} + 2 O_{2 (g)} \to CO_{2 (g)} + 2 H_{2} O_{(l)}$ 174. $In which of the following reactions, standard reaction entropy change (S) is positive and standard Gibbs energy change (G) decreases sharply with increasing temperature?$ (1) $C_{(graphite)} + \frac{1}{2} O_{2 (g)} \to C O_{(g)}$ (2) $C O_{(g)} + \frac{1}{2} O_{2 (g)} \to C O_{2 (g)}$ (3) $M g_{(s)} + \frac{1}{2} O_{2 (g)} \to Mg O_{(s)}$ (4) $\frac{1}{2} C_{(graphite)} + \frac{1}{2} O_{2 (g)} \to \frac{1}{2} C O_{2 (g)}$ 175. $A reaction has DH = - 33 kJ and DS = - 58 J/K. This reaction would be:$ (1) $spontaneous at all temperatures$ (2) $non-spontaneous at all temperatures$ (3) $spontaneous above a certain temperature$ (4) $spontaneous below a certain temperature$ 176. $Two moles of an ideal gas (C_{v} = 12.5 J K^{-1} m o l^{-1}) occupy a volume of 2 d m^{3} at 300 K. If it is heated to 320 K to increase the volume to 4 d m^{3} the entropy change is -$ (1) $11.5$ (2) $8.3$ (3) $13.1$ (4) $9.3$ 177. $Consider the following reaction at 298 K . \frac{3}{2} O_{2 (g)} ⇌ O_{3 (g)} \cdot K_{P} = 2.47 \times 10^{- 29} . Δ_{r} G^{\oplus} for the reaction is_____ kJ. (Given (R = 8.314 JK^{- 1} mol^{- 1})$ 178. $The heat of combustion of ethanol into carbon dioxide and water is -327 kcal at constant pressure. The heat evolved (in cal) at constant volume and 27°C (if all gases behave ideally) is: (R = 2 cal mol^{- 1} K^{- 1})$ 179. $The enthalpy of formation of ethane (C_{2} H_{6}) from ethylene by addition of hydrogen where the bond-energies of C - H, C - C, C = C, H - H are 414 kJ, 347 kJ, 615 kJ and 435 kJ respectively is kJ$ 180. $When 5 moles of He gas expand isothermally and reversibly at 300 K from 10 litre to 20 litre, the magnitude of the maximum work obtained is____J. [nearest integer] (Given: R = 8.3 J K^{- 1} m o l^{- 1} and log 2 = 0.3010)$