Unit 6: Thermo Dynamics — Online MCQ Test
CHEMISTRY · CLASS 11 INTERMEDIATE 1 YEAR · Telangana State Board
Practice Unit 6: Thermo Dynamics with a free chapter-wise online MCQ test.
This chapter covers: This chapter details system types state functions first second third laws of thermodynamics enthalpy heat capacity and Hess law. Students examine spontaneity Gibbs free energy chan....
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Unit 6: Thermo Dynamics — Important Questions & Answers
Which of the following is an example of an open system?
- A. A sealed flask of water
- B. A pressure cooker with closed lid
- C. A human body
- D. A thermos flask
Answer: C. A human body
A human body exchanges both matter and energy with the surroundings, so it is an open system.
A human body exchanges both matter and energy with the surroundings, so it is an open system.
Which of the following is a state function?
- A. Heat
- B. Work
- C. Internal energy
- D. Path length
Answer: C. Internal energy
Internal energy depends only on the state of the system, not on the path taken.
Internal energy depends only on the state of the system, not on the path taken.
For an exothermic reaction at constant pressure, the enthalpy change is:
- A. Positive
- B. Negative
- C. Zero
- D. Always equal to heat capacity
Answer: B. Negative
In an exothermic reaction, heat is released by the system, so ΔH is negative at constant pressure.
In an exothermic reaction, heat is released by the system, so ΔH is negative at constant pressure.
For a reaction with ΔH = +40 kJ mol⁻¹ and ΔS = +100 J mol⁻¹ K⁻¹, at what temperature does spontaneity begin? (Use T = ΔH/ΔS)
- A. 200 K
- B. 300 K
- C. 400 K
- D. 500 K
Answer: C. 400 K
Convert ΔH to 40000 J mol⁻¹. Then T = 40000/100 = 400 K, which is the threshold temperature.
Convert ΔH to 40000 J mol⁻¹. Then T = 40000/100 = 400 K, which is the threshold temperature.
Which of the following is the correct relation between heat absorbed at constant pressure and enthalpy change?
- A. q_p = ΔU
- B. q_p = −ΔH
- C. q_p = ΔH
- D. q_p = ΔG
Answer: C. q_p = ΔH
At constant pressure, the heat absorbed or released by the system equals the enthalpy change.
At constant pressure, the heat absorbed or released by the system equals the enthalpy change.