Title Chemical Thermodynamics - 03.pdf ✅

1 JEE ADVANCED 2024 Chemical Thermodynamics Single Correct (1 – 7) 1. One mole of a non-ideal gas undergoes a change of state (2.0 atm, 3.0 L, 95 K) → (4.0 atm, 5.0 L, 245K) when a change in internal energy ΔU = 30.0 L - atm. The change in enthalpy (ΔH) of the process is L-atm is: (1) 40.0 (2) 42.3 (3) 44.0 (4) not defined because pressure is not constant 2. Two mole of an ideal gas expanded isothermally and reversibly from 1 litre to 10 litre at 300 K. The enthalpy change (in kJ) for the process is: (1) 11.4 (2) -11.4 (3) 0 (4) 4.8 3. When one mole of monoatomic ideal gas T K undergoes reversible adiabatic change under a constant external pressure of 1 atm changes volume from 1 litre to 2 litre. The final temperature in kelvin would be: - (1) T (2) 2/3 (2) T + 2 3 × 0.081 (3) T (4) T − 3 2 × 0.0821 4. The direct conversion of A to B is difficult, hence it is carried out as: Given, ∆S(A→C) = 50eU; ∆S(C→D) = 30eU ; ΔS(B→D) = 20eU; where eU is entropy unit. Thus change in entropy in (A → B) is: (1) 100eU (2) 60eU (3) −100eU (4) −60eU 5. A piston filled with 0.04 mol of an ideal gas expands reversibly from 50.0 mL to 375 mL at a constant temperature of 37.0 ∘C. As it does so, it absorbs 208 J of heat. The values of q and w for the process will be: (R = 8.314 J/molK)( In 7.5 = 2.01) (1) q = −208 J, w = + 208 J (2) q = + 208 J, w = + 208 J (3) q = + 208 J, w = −208 J (4) q = −208 J, w = −208 J One more option question 6. 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 was work done] (1) ΔSx→z = ΔSx→y + ΔSy→z (2) wx→z = wx→y + wy→z (3) wx→y→z = wx→y (4) ΔSx→y→z = ΔSx→y DPP - 03
2 7. The reversible expansion of an ideal gas under adiabatic and isothermal conditions is shown in the figure. Which of the following statement(s) is (are) correct? (1) T1 = T2 (2) T3 > T1 (3) wisothermal > wadiabatic (4) ΔUisothermal > ΔUadiabatic 8. An ideal gas in a thermally insulated vessel at internal pressure = P1, volume = V1 and absolute temperature = T1 expands irreversibly against zero external pressure, as shown in the diagram. The final internal pressure, volume and absolute temperature of the gas are P2, V2 and T2 , respectively. For this expansion, (1) q = 0 (2) T2 = T1 (3) P2V2 = P1V1 (4) P2V2 γ = P1V1 γ Comprehension: 1 Chemical reactions are usually exothermic or endothermic. A balanced thermochemical equation involving physical states of reactants and products expresses the chemical changes as well as heat of reaction. Heat changes are usually expressed in terms of ΔH (at constant P) or ΔU (at constant V). The heats of reactions varies with physical state of reactants and products, conditions of constant pressure volume and temperature. Heats of combustion and heat of neutralization, heat of condensation are always exothermic. standard heat enthalpy of a compound is its heat of formation 1atm P and 25∘C. 9. The heat energy released during neutralization of leq. of HF with leq. of NaOH and with 1 eq. of CH3COOH and leq. of NaOH are respectively: (1) −16.4kcal, −12.0kcal (2) −12.0kcal, −10kcal (3) −13.7kcal in both (4) −12.0kcal, −16.4kcal 10. Heat of dissociation for H2O in H + and OH−ions is (1) −57.27 kJ/mol (2) + 57.27 kJ/mol (3) −50 kJ/mol (4) + 50 kJ/mol 11. In which case of mixing a strong acid and a base each of 1 N concentration, temperature rise is highest: (1) 20 mL acid + 30 mL alkali (2) 10 mL acid + 40 mL alkali (3) 25 mL acid + 25 mL alkali (4) 30 mL acid + 20 mL alkali 12. Heat of combustion of CH4, C2H4, C2H2 and C2H6 are −890, −1411, −1300 and −1560 kJ mol−1 . The best fuel is: (1) CH4 (2) C2H4 (3) C2H6 (4) C2H2 13. The enthalpy of which form of carbon has been supposed to be zero at 25∘C and 1 atm: (1) Graphite (2) Diamond (3) Coke (4) Charcoal 14. Molar heat capacity of diamond carbon in equilibrium with graphite carbon at constant pressure is: (1) zero (4) infinity (3) 3.4 kJ/mol (4) −3.4 kJ/mol
3 Integer Type Questions – Single Digit (0–9) 15. How many of the following have their standard heat of formation zero at 298 K. O2 (l), Cgraphite, , PBlack , Smonoclinic , I2 (solid) 16. How many of the following possess heat of neutralization less than −13.7kcal. HCl(aq. ) + NaOH(aq. ),HF(aq. ) + NaOH(aq. ), CH3COOH(aq. ) + NH4OH(aq. ), CCl3COOH(aq. ) + KOH(aq. ), C6H5COOH(aq. ) + KOH(aq. ) 17. For Au(OH)3 + 4HCl ⟶ HAuCl4 + 3H2O; ΔH = −28kcal and Au(OH)3 + 4HBr ⟶ HAuBr4 + 3H2O; ΔH = −36.8kcal If 1 mole of HAuBr4 was mixed with 4 mole of HCl, 0.44 kcal heat was absorbed. The percentage conversion of HAuBr4 to HAuCl4 is.. .... Matrix – Match Type Questions 18. Match the columns. Column I (A) Reversible isothermal expansion of an ideal gas (B) Reversible adiabatic expansion of an ideal gas (C) Adiabatic free expansion Column II (P) ΔSsys = ΔSsurr = ΔStotal = 0 (Q) ΔH = ΔU = ΔStotal = 0 (R) ΔStotal > 0 (S) q = 0 (1) A→Q; B→P, S; C→R,S (2) A → R, Q; B → R, S; C → Q, R, S (3) A → R, Q; B → P, S; C → Q, R, S (4) A → P, S; B → P, Q, R, S; C → R, S