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Chemical Thermodynamics ISC Class 11 MCQ & Practice Questions

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

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Chemical Thermodynamics Revision Guide for ISC 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 ISC 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 Chemical Thermodynamics

Concept Revision

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

Exam-style MCQs

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

Performance Practice

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

Top 20 Chemical Thermodynamics MCQs with Answers

These public questions are selected from the exact Chemical 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.

ISC Class 11 Chemistry · Chemical Thermodynamics · Very Hard

1. For reactions involving ideal gases, the relation between ΔH and ΔU is

  • A. ΔH = ΔU + ΔngRT
  • B. ΔH = ΔU - ΔngRT always
  • C. ΔH = ΔU/RT
  • D. ΔH = RT/ΔU
Answer: A
Explanation: For ideal gaseous species, PV=nRT gives ΔH=ΔU+ΔngRT.

ISC Class 11 Chemistry · Chemical Thermodynamics · Very Hard

2. Hess's law states that total enthalpy change depends on

  • A. Number of steps directly
  • B. Initial and final states, not the path
  • C. Only the catalyst
  • D. Reaction time
Answer: B
Explanation: Because enthalpy is a state function, overall ΔH is path independent.

ISC Class 11 Chemistry · Chemical Thermodynamics · Very Hard

3. In a cyclic process, the change in a state function such as internal energy is

  • A. Always positive
  • B. Always negative
  • C. Infinite
  • D. Zero
Answer: D
Explanation: The final state equals the initial state, so ΔU over a complete cycle is zero.

ISC Class 11 Chemistry · Chemical Thermodynamics · Very Hard

4. The first law of thermodynamics expresses conservation of

  • A. Volume
  • B. Energy
  • C. Mass only
  • D. Entropy only
Answer: B
Explanation: The first law states that energy cannot be created or destroyed.

ISC Class 11 Chemistry · Chemical Thermodynamics · Very Hard

5. Using the chemistry sign convention, the first law may be written as

  • A. ΔU = q + w
  • B. ΔU = q - w always
  • C. ΔU = qw
  • D. ΔU = q/w
Answer: A
Explanation: With work done on the system positive, ΔU = q + w.

ISC Class 11 Chemistry · Chemical Thermodynamics · Very Hard

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

  • A. Entropy
  • B. ΔU
  • C. ΔH
  • D. Zero
Answer: B
Explanation: With w=0, the first law gives qv=ΔU.

ISC Class 11 Chemistry · Chemical Thermodynamics · Very Hard

7. Enthalpy is defined as

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

ISC Class 11 Chemistry · Chemical Thermodynamics · Very Hard

8. At constant pressure, heat exchanged is equal to

  • A. ΔU always
  • B. Zero
  • C. -ΔH
  • D. ΔH
Answer: D
Explanation: For a constant-pressure process involving only PV work, qp=ΔH.

ISC Class 11 Chemistry · Chemical Thermodynamics · Very Hard

9. For an exothermic reaction at constant pressure, ΔH is

  • A. Zero always
  • B. Undefined
  • C. Negative
  • D. Positive
Answer: C
Explanation: Exothermic processes release heat, giving products lower enthalpy than reactants.

ISC Class 11 Chemistry · Chemical Thermodynamics · Very Hard

10. For an endothermic reaction at constant pressure, ΔH is

  • A. Equal to -T
  • B. Positive
  • C. Negative
  • D. Always zero
Answer: B
Explanation: Endothermic reactions absorb heat, so products have greater enthalpy.

ISC Class 11 Chemistry · Chemical Thermodynamics · Very Hard

11. A state function depends on

  • A. Initial and final states only
  • B. The exact path followed
  • C. Reaction speed only
  • D. Catalyst surface area
Answer: A
Explanation: The change in a state function is independent of path.

ISC Class 11 Chemistry · Chemical Thermodynamics · Very Hard

12. Which is a path function?

  • A. Internal energy
  • B. Enthalpy
  • C. Entropy
  • D. Heat
Answer: D
Explanation: Heat depends on the path by which a process occurs.

ISC Class 11 Chemistry · Chemical Thermodynamics · Very Hard

13. Internal energy is a

  • A. Catalyst property
  • B. Dimensionless constant
  • C. State function
  • D. Path function
Answer: C
Explanation: Internal energy is determined by the thermodynamic state.

ISC Class 11 Chemistry · Chemical Thermodynamics · Very Hard

14. Heat capacity is defined as heat required to raise temperature by

  • A. Ten degrees
  • B. One hundred degrees
  • C. Any amount independent of heat
  • D. One degree
Answer: D
Explanation: Heat capacity is the heat required for a unit temperature increase.

ISC Class 11 Chemistry · Chemical Thermodynamics · Very Hard

15. Specific heat capacity is heat required to raise the temperature of

  • A. Any mass by one hundred degrees
  • B. One litre of gas only
  • C. Unit mass of a substance by one degree
  • D. One mole only by ten degrees
Answer: C
Explanation: Specific heat capacity is heat per unit mass per unit temperature rise.

ISC Class 11 Chemistry · Chemical Thermodynamics · Very Hard

16. Molar heat capacity refers to heat required per

  • A. Molecule only
  • B. Mole per degree temperature rise
  • C. Gram only
  • D. Litre only
Answer: B
Explanation: Molar heat capacity is defined for one mole of substance.

ISC Class 11 Chemistry · Chemical Thermodynamics · Very Hard

17. Standard enthalpy of formation is the enthalpy change when

  • A. One mole of a compound forms from its elements in standard states
  • B. One mole decomposes completely
  • C. Any amount burns
  • D. One gram dissolves
Answer: A
Explanation: Standard formation enthalpy refers to formation of one mole from constituent elements in their standard states.

ISC Class 11 Chemistry · Chemical Thermodynamics · Very Hard

18. The standard enthalpy of formation of an element in its standard state is

  • A. Always positive
  • B. Always negative
  • C. Equal to its atomic mass
  • D. Zero
Answer: D
Explanation: By convention, ΔfH° of an element in its standard state is zero.

ISC Class 11 Chemistry · Chemical Thermodynamics · Very Hard

19. Standard enthalpy of combustion is generally

  • A. Zero
  • B. Always equal to R
  • C. Negative
  • D. Positive
Answer: C
Explanation: Combustion is usually strongly exothermic.

ISC Class 11 Chemistry · Chemical Thermodynamics · Very Hard

20. Bond dissociation enthalpy is the enthalpy needed to

  • A. Freeze a liquid
  • B. Break a specified bond in gaseous species
  • C. Form an ionic crystal
  • D. Condense a gas
Answer: B
Explanation: Bond dissociation requires energy and is defined for gaseous species.

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Chemical Thermodynamics Practice Tests

Chemical 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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