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Thermodynamics WBCHSE Class 11 MCQ & Practice Questions

Practice Thermodynamics MCQs for WBCHSE Class 11 Chemistry with answers, explanations, chapter revision and related ChemNexa mock tests.

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Thermodynamics Revision Guide for WBCHSE Class 11 Chemistry

Thermodynamics relates heat, work, internal energy, enthalpy and spontaneity. It is best learned through sign conventions and state-function logic rather than isolated memorisation.

For WBCHSE Class 11 Chemistry, revise the first law, enthalpy changes, Hess law, entropy and Gibbs free energy, then practise conceptual and numerical MCQs together.

Important Topics

  • System, surroundings and state functions
  • First law of thermodynamics
  • Enthalpy and heat capacity
  • Hess law
  • Entropy
  • Gibbs free energy and spontaneity

Important Formulae & Relationships

  • ΔU = q + w
  • At constant pressure: qp = ΔH
  • ΔH = ΔU + ΔngRT (for ideal-gas reactions)
  • ΔG = ΔH − TΔS
  • ΔG° = −RT ln K

Use formulas only after checking the required units, sign convention and assumptions for the question.

What to practise in Thermodynamics

Concept Revision

Revise definitions, principles, equations, trends and core ideas from Thermodynamics before attempting MCQs.

Exam-style MCQs

Use chapter-focused multiple-choice practice to improve accuracy, recall and application for WBCHSE Class 11 Chemistry.

Performance Practice

Attempt ChemNexa tests, review results and return to weak areas for another round of targeted revision.

Top 20 Thermodynamics MCQs with Answers

These public questions are selected from the exact Thermodynamics chapter, screened for topic relevance and deduplicated so repeated versions of the same MCQ are not shown publicly. Use them for quick revision, then sign in to attempt the complete test experience with more questions, results and performance review.

WBCHSE Class 11 Chemistry · Thermodynamics · Very Hard

1. Hess's law follows from the fact that enthalpy is:

  • A. An intensive property
  • B. A state function
  • C. A path function
  • D. Always positive
Answer: B
Explanation: Because ΔH depends only on initial and final states, reaction steps can be summed.

WBCHSE Class 11 Chemistry · Thermodynamics · Very Hard

2. According to Hess's law, the total enthalpy change is:

  • A. Independent of reaction path
  • B. Dependent on number of steps
  • C. Zero for every cycle step
  • D. Equal to activation energy
Answer: A
Explanation: Different paths connecting the same states have the same net ΔH.

WBCHSE Class 11 Chemistry · Thermodynamics · Very Hard

3. The second law introduces the thermodynamic state function:

  • A. Pressure
  • B. Entropy
  • C. Heat
  • D. Work
Answer: B
Explanation: Entropy provides a criterion for direction and spontaneity.

WBCHSE Class 11 Chemistry · Thermodynamics · Very Hard

4. Which is a state function?

  • A. Heat
  • B. Work
  • C. Path length
  • D. Internal energy
Answer: D
Explanation: Internal energy is determined by the thermodynamic state.

WBCHSE Class 11 Chemistry · Thermodynamics · Very Hard

5. Using the chemistry sign convention, the first law is:

  • A. ΔU=q+w
  • B. ΔU=q-w
  • C. ΔU=w-q
  • D. ΔU=-q-w
Answer: A
Explanation: Heat absorbed and work done on the system increase internal energy.

WBCHSE Class 11 Chemistry · Thermodynamics · Very Hard

6. For an isolated system, q and w are both zero, hence:

  • A. ΔH always positive
  • B. ΔS=0 for every process
  • C. Temperature must be zero
  • D. ΔU=0
Answer: D
Explanation: With no energy exchange, total internal energy remains constant.

WBCHSE Class 11 Chemistry · Thermodynamics · Very Hard

7. At constant volume with only PV work, heat exchanged equals:

  • A. -ΔU
  • B. Zero always
  • C. ΔU
  • D. ΔH
Answer: C
Explanation: At constant volume PV work is zero, so qv=ΔU.

WBCHSE Class 11 Chemistry · Thermodynamics · Very Hard

8. Enthalpy is defined as:

  • A. H=TS
  • B. H=U+PV
  • C. H=U-PV
  • D. H=q+w
Answer: B
Explanation: Enthalpy combines internal energy with the PV term.

WBCHSE Class 11 Chemistry · Thermodynamics · Very Hard

9. At constant pressure, heat exchanged for a PV-work process equals:

  • A. ΔH
  • B. ΔU always
  • C. ΔS
  • D. ΔG
Answer: A
Explanation: Under constant pressure and only PV work, qp=ΔH.

WBCHSE Class 11 Chemistry · Thermodynamics · Very Hard

10. For an ideal gas reaction, the relation between enthalpy and internal energy changes is:

  • A. ΔH=ΔU-ΔngRT
  • B. ΔH=ΔU+RT always
  • C. ΔH=ΔU/RT
  • D. ΔH=ΔU+ΔngRT
Answer: D
Explanation: For ideal gases, the PV contribution gives ΔngRT.

WBCHSE Class 11 Chemistry · Thermodynamics · Very Hard

11. If all coefficients in a thermochemical equation are doubled, ΔH:

  • A. Remains unchanged
  • B. Becomes zero
  • C. Doubles
  • D. Halves
Answer: C
Explanation: Enthalpy change is extensive and scales with reaction amount.

WBCHSE Class 11 Chemistry · Thermodynamics · Very Hard

12. A state function depends on:

  • A. Initial and final states only
  • B. Path only
  • C. Rate of process only
  • D. Catalyst only
Answer: A
Explanation: Changes in state functions are path independent.

WBCHSE Class 11 Chemistry · Thermodynamics · Very Hard

13. For an exothermic process at constant pressure:

  • A. ΔH>0
  • B. ΔH=0 always
  • C. ΔU must be zero
  • D. ΔH<0
Answer: D
Explanation: Heat is released by the system, giving negative enthalpy change.

WBCHSE Class 11 Chemistry · Thermodynamics · Very Hard

14. For an endothermic process at constant pressure:

  • A. ΔH=0
  • B. ΔS must be negative
  • C. ΔH>0
  • D. ΔH<0
Answer: C
Explanation: Heat absorption gives a positive enthalpy change.

WBCHSE Class 11 Chemistry · Thermodynamics · Very Hard

15. Standard enthalpy of formation is the enthalpy change when:

  • A. A bond is broken
  • B. A solid melts
  • C. One mole of compound forms from elements in standard states
  • D. One mole compound burns completely
Answer: C
Explanation: Formation enthalpy refers to formation of one mole from constituent elements in standard states.

WBCHSE Class 11 Chemistry · Thermodynamics · Very Hard

16. Standard enthalpy of formation of an element in its standard state is:

  • A. Equal to its ionisation enthalpy
  • B. Zero
  • C. Always positive
  • D. Always negative
Answer: B
Explanation: By convention it is assigned zero.

WBCHSE Class 11 Chemistry · Thermodynamics · Very Hard

17. Standard enthalpy of combustion is usually:

  • A. Negative
  • B. Positive
  • C. Zero
  • D. Undefined
Answer: A
Explanation: Combustion releases heat under ordinary thermochemical conditions.

WBCHSE Class 11 Chemistry · Thermodynamics · Very Hard

18. Bond dissociation enthalpy corresponds to:

  • A. Forming an ionic lattice only
  • B. Melting a solid
  • C. Condensing a vapour
  • D. Breaking a specified bond in gaseous species
Answer: D
Explanation: It is the enthalpy required for homolytic bond cleavage in gas phase.

WBCHSE Class 11 Chemistry · Thermodynamics · Very Hard

19. Bond breaking is generally:

  • A. Athermal always
  • B. Entropy-free
  • C. Endothermic
  • D. Exothermic
Answer: C
Explanation: Energy must be supplied to overcome bonding attraction.

WBCHSE Class 11 Chemistry · Thermodynamics · Very Hard

20. Bond formation is generally:

  • A. Impossible in gases
  • B. Exothermic
  • C. Endothermic
  • D. Always zero enthalpy
Answer: B
Explanation: Energy is released when stable bonds form.

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Thermodynamics Practice Tests

Thermodynamics Frequently Asked Questions

What causes most Thermodynamics mistakes?

Sign conventions for heat and work, confusing state functions with path functions, and using inconsistent units are common sources of error.

What does negative ΔG indicate?

For a process under the stated conditions, negative Gibbs free-energy change indicates thermodynamic spontaneity.

How should I revise Thermodynamics?

Build a one-page sign-convention and formula sheet, then practise problems that require choosing the correct relation rather than only substituting numbers.

Continue with another chapter to build connected concepts and strengthen your overall Chemistry preparation.

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