Chapter 5: Chemical Thermodynamics — Online MCQ Test
CHEMISTRY · CLASS 11 INTER I YEAR · Andhra State Board
Practice Chapter 5: Chemical Thermodynamics with a free chapter-wise online MCQ test.
This chapter covers: System Surroundings Enthalpy Entropy Gibbs free energy Heat Work Internal energy Hess law Spontaneous process.
AI-generated questions from basic to board-exam level, with instant results and explanations.
Chapter 5: Chemical Thermodynamics — Important Questions & Answers
Which of the following best defines a thermodynamic system?
- A. The portion of the universe selected for study
- B. The entire universe excluding surroundings
- C. Only the container used in an experiment
- D. Only the reactants in a chemical reaction
Answer: A. The portion of the universe selected for study
A thermodynamic system is the part of the universe chosen for study. Everything outside it is called the surroundings.
A thermodynamic system is the part of the universe chosen for study. Everything outside it is called the surroundings.
Which type of system can exchange both matter and energy with its surroundings?
- A. Open system
- B. Closed system
- C. Isolated system
- D. Adiabatic system
Answer: A. Open system
An open system allows exchange of both matter and energy with the surroundings.
An open system allows exchange of both matter and energy with the surroundings.
If a system absorbs heat from the surroundings, the sign of q is:
- A. negative
- B. positive
- C. zero
- D. cannot be determined
Answer: B. positive
Heat absorbed by the system is taken as positive.
Heat absorbed by the system is taken as positive.
For a process with ΔH = -50 kJ and ΔS = -0.10 kJ K⁻¹ at 300 K, the sign of ΔG is:
- A. positive
- B. negative
- C. zero
- D. cannot be determined
Answer: B. negative
Using ΔG = ΔH - TΔS = -50 - 300(-0.10) = -20 kJ, so ΔG is negative.
Using ΔG = ΔH - TΔS = -50 - 300(-0.10) = -20 kJ, so ΔG is negative.
For a reaction, if ΔH = +80 kJ mol⁻¹ and ΔS = +200 J K⁻¹ mol⁻¹, the temperature above which the reaction becomes spontaneous is:
- A. 400 K
- B. 800 K
- C. 1200 K
- D. 1600 K
Answer: B. 800 K
Spontaneity requires ΔG < 0, so T > ΔH/ΔS = 80,000/200 = 400 K. Among the options, 400 K is the threshold, so spontaneity begins above it.
Spontaneity requires ΔG < 0, so T > ΔH/ΔS = 80,000/200 = 400 K. Among the options, 400 K is the threshold, so spontaneity begins above it.