Thermodynamics PYQs Set 6 (PDF)

Set 6 of 14 · Questions 151-180 of 393

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Mere Teacher · Previous Year Questions NEET Chemistry · Thermodynamics · Set 6 (Q151-180)
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151. $Two moles of an ideal gas (C_{v} = 12.5 J K^{-1} m o l^{-1}) occupy a volume of 2 d m^{3} at 300 K. If it is heated to 320 K to increase the volume to 4 d m^{3} the entropy change is -$ (1) $11.5$ (2) $8.3$ (3) $13.1$ (4) $9.3$ 152. $Which of the following option the first compound has less entropy than second:$ (1) $(i) aqueous solution of 1 M of M g C l_{2} (ii) aqueous solution of 1 M of NaCl$ (2) $(i) B r_{2} liquid at 25ºC (ii) B r_{2} liquid at 20ºC$ (3) $(i) HgO solid (ii) HgS solid$ (4) $(i) B r_{2} liquid (ii) I_{2} solid$ 153. $When 2.0 g sucrose is oxidised forming CO_{2 (g)} and H_{2} O_{(l)} the internal energy changes by 24 kJ . Calculate the value of Δ H at 298 K in kJ / mol . (Molar mass of sucrose = 342 g mol^{- 1})$ (1) $2014 kJ$ (2) $- 4104 kJ$ (3) $- 5612 kJ$ (4) $8208 kJ$ 154. $The standard enthalpies of formation of C O_{2} (g), H_{2} O(l) and glucose(s) at 25ºC are -400 kJ/mol, -300 kJ/mol and -1300 kJ/mol, respectively. The standard enthalpy of combustion per gram of glucose at 25ºC is$ (1) $+2900 kJ$ (2) $- 2900 kJ$ (3) $-16.11 kJ$ (4) $+ 16.11 kJ$ 155. $When 1 mol of gas is heated at constant volume temperature is raised from 298 to 308 K. Heat supplied to the gas is 500 J. Then which statement is correct?$ (1) $q = w = 500 J, Δ E = 0$ (2) $q = Δ E = 500 J, w = 0$ (3) $ΔE=w=500J,q=0$ (4) $Δ E = 0, q = w = - 500 J$ 156. $If 900 J/g of heat is exchanged at boiling point of water, then what is increase in entropy$ (1) $43.4 J/mole$ (2) $87.2 J/mole$ (3) $900 J/mole$ (4) $Zero$ 157. $Maximum entropy will be in which of the following$ (1) $Ice$ (2) $Liquid water$ (3) $Snow$ (4) $Water vapours$ 158. $For which one of the following equations is Δ H_{react}^{o} equal to Δ H_{f}^{o} for the product?$ (1) $N_{2 (g)} + O_{3 (g)} \to N_{2} O_{3 (g)}$ (2) $C H_{4 (g)} + 2 C l_{2 (g)} \to C H_{2} C l_{2 (l)} + 2 HC l_{(g)}$ (3) $X e_{(g)} + 2 F_{2 (g)} \to Xe F_{4 (g)}$ (4) $2 C O_{(g)} + O_{2 (g)} \to 2 C O_{2 (g)}$ 159. $An ideal gas undergoes isothermal compression from 5 m^{3} to 1 m^{3} against a constant external pressure of 4 Nm^{- 2} Heat released in this process is used to increase the temperature of 1 mole of Al . If molar heat capacity of Al is 24 J mol^{- 1} K^{- 1},the temperature of AI increases by:$ (1) $3 2 K$ (2) $2 K$ (3) $\frac{2}{3} K$ (4) $1 K$ 160. $The molar heat capacity of water at constant pressure, C, is 75 J K^{- 1} mo l^{- 1} . When 1.0 kJ of heat is supplied to 100 g of water which isfree to expand, the increase in temperature of water is$ (1) $1.2 K$ (2) $2.4 K$ (3) $4.8 K$ (4) $6.6 K$ 161. $A \to D is an endothermic reaction occurring in three steps (elementary). (i) A \to B Δ H_{i} = + ve (ii) B \to C Δ H_{ii} = - ve (iii) C \to D Δ H_{iii} = - ve Which of the following graphs between potential energy (y -axis) vs reaction coordinate (x -axis) correctly represents the reaction profile of A \to D ?$ (1) (2) (3) (4) 162. $If one mole of ammonia and one mole of hydrogen chloride are mixed in a closed container to form ammonium chloride gas, then$ (1) $Δ H < Δ U$ (2) $there is no relationship$ (3) $Δ H > Δ U$ (4) $Δ H = Δ U$ 163. $Statement-1 : There is a natural asymmetry between converting work to heat and converting heat to work. Statement-2 : No process is possible in which the sole result is the absorption of heat form a reservoir and its complete conversion into work.$ (1) $Statement-1 is True, Statement-2 is True; Statement-2 is a correct explanation for Statement-1.$ (2) $Statement-1 is True, Statement-2 is True; Statement-2 is NOT a correct explanation for Statement-1$ (3) $Statement-1 is True, Statement-2 is False$ (4) $Statement-1 is False, Statement-2 is True$ 164. $A process has Δ H = 200 J mol^{- 1} and Δ S = 40 JK^{- 1} mol^{- 1} Out of the values given below, choose the minimum temperature above which the process will be spontaneous:$ (1) $20 K$ (2) $12 K$ (3) $5 K$ (4) $4 K$ 165. $Which of the following graphs between pressure ' p ' versus volume ' V ' represents the maximum work done?$ (1) (2) (3) (4) 166. $Two blocks of the same metal having same mass and at temperature T_{1}, and T_{2}, respectively, are brought in contact with each other and allowed to attain thermal equilibrium at constant pressure. The change in entropy, Δ S, for this process is :$ (1) $C_{P} ln (\frac{( T _{1} + T _{2} ) ^{2}}{4 T _{1} T _{2}})$ (2) $2 C_{P} ln (\frac{( T _{1} + T _{2} ) ^{\frac{1}{2}}}{T _{1} T _{2}})$ (3) $2 C_{P} ln (\frac{T _{1} + T _{2}}{4 T _{1} T _{2}})$ (4) $2 C_{P} ln (\frac{T _{1} + T _{2}}{2 T _{1} T _{2}})$ 167. $If C (diamond ) \to C (graphite ) + XkJmol^{- 1} C (diamond ) + O_{2} (g) \to CO_{2} (g) + YkJmol^{- 1} C (graphite) + O_{2} (g) \to CO_{2} (g) + ZkJmol^{- 1} at constant temperature. Then$ (1) $X = - Y + Z$ (2) $- X = Y + Z$ (3) $X = Y + Z$ (4) $X = Y - Z$ 168. $Heat of combustion Δ H for C_{(s)}, H_{2 (g)} and C H_{4 (g)} are - 94, - 68 and - 213 kcal/mol, then Δ H for C_{(s)} + 2 H_{2 (g)} \to C H_{4 (g)} is$ (1) $- 17 kcal$ (2) $- 111 kcal$ (3) $- 170 kcal$ (4) $- 85 kcal$ 169. $If, Δ H > 0 and Δ S > 0, the reaction can proceed spontaneously at\dots\dots\dots.$ (1) $low temperature$ (2) $high temperature$ (3) $all temperature$ (4) $will never be spontaneous$ 170. $For silver, C_{p} (JK^{- 1} mol^{- 1}) = 23 + 0.01 T If the temperature (T) of 3 moles of silver is raised from 300 K to 1000 K at 1 atm pressure, the value of Δ H will be close to:$ (1) $62 kJ$ (2) $16 kJ$ (3) $21 kJ$ (4) $13 kJ$ 171. $The enthalpy change for a given reaction at 298 K is - x J m o l^{-1} (x being positive). If the reaction occurs spontaneously at 298 K, the entropy change at that temperature$ (1) $Can be negative but numerically larger than x/298$ (2) $Can be negative but numerically smaller than x/298$ (3) $Cannot be negative$ (4) $Cannot be positive$ 172. $Standard state Gibbs free energy change for isomerization reaction cis‐2‐pentene \equiv trans - 2‐pentene is - 3.67 kJ/mol at 400 K. If more trans‐2‐pentene is added to the reaction vessel, then$ (1) $equilibrium remains unaffected$ (2) $equilibrium is shifted in the forward direction$ (3) $more cis‐2‐pentene is formed$ (4) $additional trans‐2‐pentene is formed.$ 173. $In an endothermic reaction, the value of Δ H is$ (1) $negative$ (2) $positive$ (3) $zero$ (4) $constant.$ 174. $What is the amount of work done when two moles of ideal gas is compressed from a volume of 1 m^{3} to 10 dm^{3} at 300 K against a pressure of 100 kPa ?$ (1) $99 kJ$ (2) $- 99 kJ$ (3) $114.9 kJ$ (4) $- 114.9 kJ$ 175. $In which of the following process, a maximum increase in entropy is observed?$ (1) $Melting of ice$ (2) $Sublimation of naphthalene$ (3) $Condensation of water$ (4) $Dissolution of salt in water$ 176. $Which of the following is an intensive property?$ (1) $Viscosity$ (2) $Surface tension$ (3) $Temperature$ (4) $All of these$ 177. $Let us consider an endothermic reaction which is non-spontaneous at the freezing point of water. However, the reaction is spontaneous at boiling point of water. Choose the correct option.$ (1) $Both ΔH and ΔS are (- ve)$ (2) $ΔH is (- ve) but ΔS is (+ ve)$ (3) $ΔH is (+ ve) but ΔS is (- ve)$ (4) $Both ΔH and ΔS are (+ ve)$ 178. $Lattice enthalpy for NaCl is + 788 kJ mol^{- 1} and Δ H^{\circ}_{hyd} = - 784 kJ mol^{- 1} . Enthalpy of solution of NaCl is$ (1) $+ 572 kJ mol^{- 1}$ (2) $+ 4 kJ mol^{- 1}$ (3) $- 572 kJ mol^{- 1}$ (4) $- 4 kJ mol^{- 1}$ 179. $The first law of thermodynamics for isothermal process is$ (1) $q = - W$ (2) $Δ U = W$ (3) $Δ U = q$ (4) $Δ U = - q_{v}$ 180. $If the standard enthalpy change (Δ_{r} H^{\circ}) for a certain reaction at 298 K and constant pressure is - 1860 kJ mol^{- 1}, the standard entropy change (Δ_{sys} S^{\circ}) of the same reaction is - 550 J K^{- 1} mol^{- 1}, which one of the following statements is correct?$ (1) $Δsys S\circ+Δsurr S\circ=-7692 J mol^{- 1} K-1, the reaction is spontaneous$ (2) $Δsys S\circ+Δsurr S\circ=-5692 J mol^{- 1} K-1, the rcaction is non-spontaneous$ (3) $Δsys S\circ+Δsurr S\circ=+5692 J mol^{- 1} K-1, the reaction is spontaneous$ (4) $Δsys S\circ+Δsurr S\circ=+7692 J mol^{- 1} K-1, the reaction is non-spontaneous$