Unit 13: Thermodynamics — Online MCQ Test
PHYSICS · CLASS 11 INTERMEDIATE 1 YEAR · Telangana State Board
Practice Unit 13: Thermodynamics with a free chapter-wise online MCQ test.
This chapter covers: Focusing on thermal energy conversion this chapter details thermal equilibrium zeroth law first law second law of thermodynamics reversible irreversible processes and Carnot engine....
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Unit 13: Thermodynamics — Important Questions & Answers
Which law of thermodynamics defines thermal equilibrium and forms the basis for temperature measurement?
- A. First law of thermodynamics
- B. Zeroth law of thermodynamics
- C. Second law of thermodynamics
- D. Third law of thermodynamics
Answer: B. Zeroth law of thermodynamics
The zeroth law states that if two systems are each in thermal equilibrium with a third system, they are in thermal equilibrium with each other. This law is the foundation of temperature measurement.
The zeroth law states that if two systems are each in thermal equilibrium with a third system, they are in thermal equilibrium with each other. This law is the foundation of temperature measurement.
In thermodynamics, the internal energy of a system is a ____ quantity.
- A. vector
- B. path-dependent
- C. state
- D. zero always
Answer: C. state
Internal energy depends only on the state of the system, not on the path followed to reach that state. Hence, it is a state function.
Internal energy depends only on the state of the system, not on the path followed to reach that state. Hence, it is a state function.
A gas is heated and expands at constant pressure. If it absorbs 500 J of heat and does 200 J of work, what is the change in internal energy?
- A. 700 J
- B. 300 J
- C. -300 J
- D. -700 J
Answer: B. 300 J
Using the first law, ΔU = Q - W = 500 J - 200 J = 300 J. The internal energy increases by 300 J.
Using the first law, ΔU = Q - W = 500 J - 200 J = 300 J. The internal energy increases by 300 J.
Which of the following best explains why no heat engine can be 100% efficient?
- A. Because work output is always negative
- B. Because some heat must be rejected to a colder reservoir
- C. Because internal energy can never change
- D. Because temperature cannot remain constant
Answer: B. Because some heat must be rejected to a colder reservoir
According to the second law of thermodynamics, a heat engine must reject some heat to a cold reservoir. Hence, complete conversion of heat into work is impossible.
According to the second law of thermodynamics, a heat engine must reject some heat to a cold reservoir. Hence, complete conversion of heat into work is impossible.
Which of the following is the most accurate statement about the first law of thermodynamics?
- A. It states that entropy of the universe always decreases
- B. It is a law of conservation of energy applied to thermodynamic systems
- C. It gives the maximum efficiency of all engines
- D. It states that heat can flow only from cold to hot
Answer: B. It is a law of conservation of energy applied to thermodynamic systems
The first law expresses conservation of energy: heat supplied to a system is used to increase internal energy and do work. It does not by itself determine the direction of processes.
The first law expresses conservation of energy: heat supplied to a system is used to increase internal energy and do work. It does not by itself determine the direction of processes.