Change of state and latent heat - One Line Questions

1. What is the melting point of ice at standard atmospheric pressure? — 0 degrees Celsius
2. The boiling point of water at standard atmospheric pressure is: — 100 degrees Celsius
3. The latent heat of fusion for a substance is the heat required to change: — 1 kg of solid to 1 kg of liquid at its melting point
4. The latent heat of vaporization of a substance is the energy required to change: — 1 kg of liquid to 1 kg of gas at boiling point
5. If 5 kg of ice at 0°C is melted into water at 0°C, how much heat energy is absorbed? (Latent heat of fusion of ice = 3.34 x 10^5 J/kg) — 1.67 x 10^6 J
6. If 2 kg of water at 100°C is converted into steam at 100°C, how much heat energy is absorbed? (Latent heat of vaporization of water = 2.26 x 10^6 J/kg) — 4.52 x 10^6 J
7. The latent heat of vaporization for water at its boiling point is approximately: — 2.26 x 10^6 J/kg
8. The specific latent heat of fusion of ice is approximately: — 3.34 x 10^5 J/kg
9. What is the value of the latent heat of fusion of water in SI units? — 3.34 x 10^5 J/kg
10. If the specific latent heat of fusion of ice is 3.34 x 10^5 J/kg, how much heat is needed to convert 20 g of ice at -10°C to water at 0°C? (Specific heat of ice = 2100 J/kg°C) — 7348 J
11. If 10 g of a solid melts completely at its melting point by absorbing 840 J of heat, what is the specific latent heat of fusion? — 84 J/g
12. When steam at 100°C condenses into water at 100°C, heat is: — Released
13. The process where a liquid turns into a gas below its boiling point is called: — Evaporation
14. Which of the following processes involves the release of latent heat? — Condensation of water vapor
15. A substance changes from solid to liquid at a fixed temperature called its: — Melting point
16. Which of the following processes involves the absorption of latent heat? — Melting of ice
17. Latent heat is defined as the heat energy absorbed or released during a change of state at: — Constant temperature and constant pressure
18. If the pressure on the surface of water is increased, its boiling point will: — Increase
19. Which of the following statements about phase transitions is correct? — During melting, heat is absorbed.
20. Which of the following statements is FALSE regarding a change of state? — The kinetic energy of molecules changes significantly.
21. Which of the following best describes the energy change during sublimation? — Energy is absorbed.
22. The process of changing from solid to gas without passing through the liquid state is called: — Sublimation
23. Dry ice (solid CO2) sublimes at atmospheric pressure. This process requires: — Heat absorption from the surroundings
24. When a liquid evaporates, it causes cooling because: — Heat is absorbed from the surroundings.
25. The phenomenon of Regelation is observed when: — Ice melts faster under pressure.
26. During the melting of ice at 0°C, the heat absorbed is used to: — Increase the potential energy of water molecules by breaking the bonds.
27. Consider the process of boiling water. During boiling, the energy supplied is primarily used to: — Increase the potential energy of water molecules by separating them.
28. During a change of state, such as melting or boiling, the temperature of the substance: — Remains constant
29. What happens to the internal energy of a substance when it melts at constant temperature? — It increases.
30. What is the unit of specific latent heat? — J/kg
31. Which type of latent heat is involved when ice melts into water? — Latent heat of fusion
32. If the latent heat of fusion of a substance is Lf and its latent heat of vaporization is Lv, then usually: — Lv > Lf
33. Which of the following phenomena involves a change of state from liquid to gas at a constant temperature? — Boiling
34. Which phase transition involves the greatest change in intermolecular potential energy per unit mass? — Vaporization
35. Which of the following phase transitions is exothermic (releases heat)? — Condensation
36. Which of the following phase changes requires the most energy per kilogram for water? — Boiling 1 kg of water at 100°C to steam at 100°C
37. The specific latent heat of vaporization is generally higher than the specific latent heat of fusion for most substances because: — More energy is needed to overcome intermolecular forces in the liquid state to form a gas.
38. When water boils, the molecules gain energy to: — Break free from intermolecular forces.
39. The amount of heat required to change 1 kg of a solid into liquid at its melting point is given by: — Q = mL
40. The triple point of a substance is the temperature and pressure at which: — Solid, liquid, and gas coexist in equilibrium
41. The heat absorbed or released during a change of state is called: — Latent heat
42. The energy required to convert 1 gram of a liquid into vapor at its boiling point without any change in temperature is known as: — Specific latent heat of vaporization
43. A substance is heated at a constant rate. Its temperature-time graph shows a plateau during melting and boiling. The slope of the plateau represents: — Latent heat of fusion or vaporization
44. The heat required to raise the temperature of 1 kg of a substance by 1°C is called its: — Specific heat capacity
45. The change of state from gas to solid without passing through the liquid state is called: — Deposition
46. Evaporation is a surface phenomenon. Which factor does NOT affect the rate of evaporation? — Pressure of the gas above the liquid
47. The boiling point of a liquid is affected by: — The external pressure
48. A pressure cooker cooks food faster because: — The pressure inside is higher, raising the boiling point of water.
49. The process of changing from gas to liquid is called: — Condensation
50. Which of the following has the highest specific latent heat of fusion? — Ice
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