Changes of State and Internal Energy Quiz
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5 questions, one answer each
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1. Which of the following best defines internal energy?
- A. The total kinetic and potential energy of the particles in a substance
- B. The temperature of a substance measured in degrees Celsius
- C. The amount of heat energy that flows from a hot object to a cold object
- D. The energy required to completely melt a solid at its melting point
2. During the melting of ice at 0 °C, the temperature remains constant. What happens to the internal energy?
- A. Internal energy decreases as heat is removed
- B. Internal energy increases as the potential energy of particles increases
- C. Internal energy stays the same because temperature is constant
- D. Internal energy decreases because kinetic energy decreases
3. A sample of water is heated from liquid to steam. Which statement correctly distinguishes between the two changes of state involved?
- A. Both evaporation and condensation occur simultaneously at the boiling point
- B. Evaporation occurs at the boiling point and requires the specific latent heat of vaporisation; condensation is the reverse process
- C. Evaporation requires the specific latent heat of fusion; condensation requires the specific latent heat of vaporisation
- D. Both evaporation and condensation occur at the same temperature for all substances
4. Calculate the energy required to melt 2.5 kg of a substance with a specific latent heat of fusion of 3.3 × 10⁵ J/kg. Use Q = mL.
- A. 1.32 × 10⁵ J
- B. 8.25 × 10⁵ J
- C. 8.25 × 10⁶ J
- D. 1.32 × 10⁶ J
5. A solid undergoes sublimation. Which of the following correctly describes what happens and why temperature remains constant during this process?
- A. Particles move from solid directly to gas state; temperature is constant because all heat energy goes into increasing kinetic energy
- B. Particles move from solid directly to gas state; temperature is constant because all heat energy goes into increasing potential energy as particles separate
- C. Particles melt first then evaporate; temperature is constant because the substance reaches equilibrium
- D. Particles gradually increase in kinetic energy until they become a gas at a lower temperature