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Chemistry - Thermodynamics (C)

Practise 73 COMEDK previous year questions on Thermodynamics (C), compiled from papers spanning 2012 to 2026. Each question is pulled directly from the actual exam paper it appeared in, so you're practising in the exact style and difficulty COMEDK tests.

Thermodynamics (C) has been asked in 15 of the 15 years of COMEDK papers analysed (2012–2026), with 73 questions in all. 34% of them were easy, 56% moderate and 10% tough. Most of its questions came from 2025, with 12 questions that year. In the last three years (2024–2026) it had 30 questions across 10 papers, about 3 per paper.

The chapter's 5 topics are not weighted equally: Laws of Thermochemistry and Enthalpy Change (25 questions, 34%), First Law and Basic Fundamentals of Thermodynamics (23 questions, 32%), and Third law of thermodynamics (13 questions, 18%) have been asked the most. Over the last five years the most frequent topics have been First Law and Basic Fundamentals of Thermodynamics (16), Laws of Thermochemistry and Enthalpy Change (14), and Third law of thermodynamics (6). Laws of Thermochemistry and Enthalpy Change has produced the most tough questions (5).

  1. 1Ozone is formed by the reaction . Given O=O bond energy is 498.0 kJ , the average bond energy of ozone is:09 May, 2026 (S1)Laws of Thermochemistry and Enthalpy Change
  2. 2and for a reaction are 35.5 kJ and 83.6 J respectively. Assuming that and do not vary with temperature, the reaction is spontaneous when:09 May, 2026 (S1)Third law of thermodynamics
  3. 3The heat of combustion of carbon to is -393.5 kJ . The heat released on the formation of 35.2 g of by combustion of C is:09 May, 2026 (S1)Laws of Thermochemistry and Enthalpy Change
  4. 4Identify the INCORRECT statement09 May, 2026 (S2)Entropy and Second law of thermodynamics
  5. 5The standard enthalpies of formation of CH (g), CO (g) and H O(l) are kJ mol , kJ mol and kJ mol respectively. Then the enthalpy change for 09 May, 2026 (S2)Laws of Thermochemistry and Enthalpy Change
  6. 6For an ideal gas undergoing an isothermal change, there is09 May, 2026 (S2)First Law and Basic Fundamentals of Thermodynamics
  7. 7The enthalpy change accompanying the freezing of 18 g of water at to ice at is: [Given: at ]25 May, 2025 (Shift)Laws of Thermochemistry and Enthalpy Change
  8. 8and were found to be both positive for a reversible reaction at temperature ' T '. If the equilibrium temperature is , the reaction will be 25 May, 2025 (Shift)Third law of thermodynamics
  9. 9When the combustion of one molecule of liquid heptane is carried out at a constant temperature ' ', the difference between and is equal to:25 May, 2025 (Shift)First Law and Basic Fundamentals of Thermodynamics
  10. 10Given that the standard enthalpy of combustion of and are -393.3 and respectively and the standard enthalpy of formation of is . What is of 10 May, 2025 (S1)Laws of Thermochemistry and Enthalpy Change
  11. 110.4 g of Propane burns completely at 300 K in a bomb calorimeter. The temperature of the calorimeter and surrounding water rises by . If the10 May, 2025 (S1)First Law and Basic Fundamentals of Thermodynamics
  12. 12For a reaction , the and are and respectively at 298 K . Find the free energy change in .10 May, 2025 (S1)Third law of thermodynamics
  13. 13For a hypothetical chemical reaction Heat , which one of the following combinations of state variables would support the spontaneity of the 10 May, 2025 (S2)Third law of thermodynamics
  14. 14For the reaction , (AB) . The bond dissociation enthalpies of , and are in the ratio 1 : 0.75 : 1. What is the bond dissociation enthalpy of10 May, 2025 (S2)Laws of Thermochemistry and Enthalpy Change
  15. 15The Enthalpy of combustion of 1.0 mole of a reactive metal X at and 1.0 bar pressure to form a solid oxide (XO) is . The Internal energy cha10 May, 2025 (S2)First Law and Basic Fundamentals of Thermodynamics
  16. 16In the decomposition of limestone to lime, the values of and are and . Calculate the temperature above which conversion of limestone to lime10 May, 2025 (S3)Third law of thermodynamics
  17. 17Two moles of an ideal gas at 1 bar pressure and 298 K is expanded into vacuum to double the volume. The work done is:10 May, 2025 (S3)First Law and Basic Fundamentals of Thermodynamics
  18. 18The enthalpies of combustion of (graphite) and are and at and 1 atm pressure. The enthalpy of formation of ethane is:10 May, 2025 (S3)Laws of Thermochemistry and Enthalpy Change
  19. 19At Constant volume, the heat required to raise the temperature of of an ideal gas at STP by is 12.0 calories. The of the gas is ____________2024 (Afternoon Shift)First Law and Basic Fundamentals of Thermodynamics
  20. 20The correct option for free expansion of an ideal gas under adiabatic condition is:2024 (Afternoon Shift)First Law and Basic Fundamentals of Thermodynamics
  21. 21The of and are 16.0 and respectively. The heat of dimerisation of in cal is :2024 (Afternoon Shift)Laws of Thermochemistry and Enthalpy Change
  22. 225.0 moles of an Ideal gas at 3.0 atm pressure and is compressed isothermally to half its volume by application of an external pressure of . 2024 (Evening Shift)First Law and Basic Fundamentals of Thermodynamics
  23. 23The Enthalpy of combustion of at and 1.0 atm pressure is . What is the Internal energy change for this reaction?2024 (Evening Shift)First Law and Basic Fundamentals of Thermodynamics
  24. 24Given : isomerisation of Cyclopropane to Propene What is the standard enthalpy of combustion of Cyclopropane?2024 (Evening Shift)Laws of Thermochemistry and Enthalpy Change
  25. 25At 300 K , one mole of ideal gas in thermal contact with surrounding expands isothermally from 1.0 L to 2.0 L against a constant pressure of2024 (Memory Based)Entropy and Second law of thermodynamics
  26. 26One mole of an ideal gas for which is heated reversibly at constant pressure of 1 atm from to will be2024 (Memory Based)First Law and Basic Fundamentals of Thermodynamics
  27. 27Given the bond enthalpies of is . is is and is , heat of formation of hydrazine in the gas phase (in ) is2024 (Memory Based)Laws of Thermochemistry and Enthalpy Change
  28. 28The standard enthalpy of formation of , the standard enthalpy of sublimation of Carbon and the bond dissociation enthalpy of Hydrogen gas ar2024 (Morning Shift)Laws of Thermochemistry and Enthalpy Change
  29. 29Given: of is and of is . Calculate the equilibrium constant for the cyclic polymerisation of Ethyne to Benzene at .2024 (Morning Shift)Third law of thermodynamics
  30. 30If the enthalpy of formation of a diatomic molecule is and the bond dissociation energies of and and are in the ratio , what is the bond dis2024 (Morning Shift)Laws of Thermochemistry and Enthalpy Change
  31. 31Gaseous Nitrous oxide decomposes at to form Nitrogen gas and Oxygen gas. The for the reaction at pressure and is . Calculate Internal energy2023 (Evening Shift)First Law and Basic Fundamentals of Thermodynamics
  32. 32If 2 moles of are completely burnt of heat is liberated. If for and are -410 and per mole respectively then the heat of formation of is2023 (Memory Based)Laws of Thermochemistry and Enthalpy Change
  33. 33For an adiabatic change in a system, the condition which is applicable is2023 (Memory Based)First Law and Basic Fundamentals of Thermodynamics
  34. 34If 2 moles of are completely burnt and of heat is liberated. If for and are and per mole respectively, then the heat of formation of is2023 (Morning Shift)Laws of Thermochemistry and Enthalpy Change
  35. 35For an adiabatic change in a system, the condition which is applicable is2023 (Morning Shift)First Law and Basic Fundamentals of Thermodynamics
  36. 36Which of the following are not path functions? I. II. W II. IV.2022First Law and Basic Fundamentals of Thermodynamics
  37. 37The relation between work done in reversible and irreversible process is2022First Law and Basic Fundamentals of Thermodynamics
  38. 38In which of the following changes, entropy decreases?2022Entropy and Second law of thermodynamics
  39. 39The difference between heat capacity at constant pressure and heat capacity at constant volume is2022First Law and Basic Fundamentals of Thermodynamics
  40. 40When the expansion of a gas occurs in vaccum and at constant volume, then2021First Law and Basic Fundamentals of Thermodynamics
  41. 41The melting of ice2021Entropy and Second law of thermodynamics
  42. 42The change in the energy of system if of heat energy are added to a system and system does of work on the surroundings will be2021First Law and Basic Fundamentals of Thermodynamics
  43. 43Which of the following is an intensive property?2020System and surrounding
  44. 44Thermodynamic standard conditions of temperature and pressure are2020System and surrounding
  45. 45In which of the following process, a maximum increase in entropy is observed?2020Entropy and Second law of thermodynamics
  46. 46Considering the reaction, The signs of and respectively are2020Third law of thermodynamics
  47. 47Entropy of the universe is2020Entropy and Second law of thermodynamics
  48. 48The standard temperature used in thermo chemical calculations is2019System and surrounding
  49. 49Which of the following is an intensive property?2019System and surrounding
  50. 50A reaction is spontaneous at all temperature, when2019Third law of thermodynamics

Frequently Asked Questions

1.How many questions are available for Thermodynamics (C)?

This chapter includes 73 questions compiled from COMEDK papers spanning 2012 to 2026.

2.Are these questions only from COMEDK, or from other exams too?

These are COMEDK questions specifically for the Thermodynamics (C) chapter. Questions from other exams like JEE Main or NTA Abhyas (JEE Main) are organised separately under their respective exam sections.

3.Is Thermodynamics (C) an important chapter for COMEDK Chemistry?

Thermodynamics (C) has appeared in 15 of the 15 years of COMEDK papers covered here, with 73 questions across 24 papers - about 3 per paper it appears in.

4.What is the difficulty level of Thermodynamics (C) questions in COMEDK?

Of the 73 questions analysed for this chapter, 34% are easy, 56% moderate and 10% tough. 2025 had the most, with 12 questions.

5.Which topics in Thermodynamics (C) should I focus on?

These topics have carried the most weightage in Thermodynamics (C):

  • Laws of Thermochemistry and Enthalpy Change - 25 questions (34%)
  • First Law and Basic Fundamentals of Thermodynamics - 23 questions (32%)
  • Third law of thermodynamics - 13 questions (18%)
  • Laws of Thermochemistry and Enthalpy Change has produced the most tough questions (5).
6.Is Thermodynamics (C)'s weightage in COMEDK going up or down?

Across all 24 papers analysed, Thermodynamics (C) has averaged about 3.0 questions per paper. In the last three years (2024–2026), that average has stayed about the same, at about 3.0 questions per paper. Use the year-wise numbers on this page for the exact trend before you decide how much time to give it.