Skip to content11. The First Law of Thermodynamics is a statement of the principle of:
- A) Conservation of mass
- B) Conservation of energy
- C) Conservation of momentum
- D) Conservation of charge
- Answer: B
12. Which of the following equations represents the First Law of Thermodynamics?
- A) ΔU = Q + W
- B) ΔU = Q – W
- C) ΔU = Q × W
- D) ΔU = Q/W
- Answer: B
13. In the First Law of Thermodynamics, ‘Q’ represents:
- A) Work done
- B) Heat transfer
- C) Change in internal energy
- D) Entropy change
- Answer: B
14. If the work done by the system is positive, it indicates that:
- A) Work is done on the system
- B) The system is losing energy
- C) The system is gaining energy
- D) Work is done by the system on the surroundings
- Answer: D
15. Which of the following processes is isothermal?
- A) Heating of a gas at constant pressure
- B) Compression of a gas at constant temperature
- C) Expansion of a gas at constant volume
- D) Heating of a gas without any heat loss
- Answer: B
16. Hess’s Law states that:
- A) The total enthalpy change of a reaction is the sum of the enthalpy changes of individual steps
- B) Energy cannot be created or destroyed
- C) The enthalpy change depends on the pathway taken
- D) The heat of formation is always negative
- Answer: A
17. In an adiabatic process, which of the following is true?
- A) Heat is exchanged with the surroundings
- B) The system remains at constant temperature
- C) No heat is exchanged with the surroundings
- D) The internal energy remains constant
- Answer: C
18. If a gas expands in a piston and does 100 J of work while absorbing 50 J of heat, what is the change in internal energy?
- A) -50 J
- B) 50 J
- C) 150 J
- D) 100 J
- Answer: B
19. When a chemical reaction occurs in a closed system, the heat absorbed or released is called:
- A) Enthalpy
- B) Entropy
- C) Heat capacity
- D) Specific heat
- Answer: A
20. Which statement about enthalpy (H) is correct?
- A) H is always negative
- B) H is independent of temperature and pressure
- C) H is a state function
- D) H does not change during a phase transition
- Answer: C
