liquid alcohol will change to vapor when its temperature reaches the A. boiling point B. fusing point C. freezing point D. melting point
Actually liquid alcohol has a vapor pressure even at room temperature; however, I think the spirit of the question calls for answer A.
The correct answer is A. boiling point.
To understand this, let's go over the definitions of each term:
A. Boiling point: The temperature at which a substance changes from a liquid to a gas (vapor) at a constant pressure. When the temperature of the liquid alcohol reaches its boiling point, it will evaporate and turn into a vapor.
B. Fusing point: The temperature at which a solid substance changes from a solid to a liquid when heat is applied. This term is typically used for solids, not for liquids.
C. Freezing point: The temperature at which a liquid changes to a solid. When the temperature of a liquid alcohol reaches its freezing point, it will solidify, not vaporize.
D. Melting point: The temperature at which a solid changes to a liquid. This term is also typically used for solids, not for liquids.
Therefore, the correct answer is A. boiling point because it describes the temperature at which a liquid alcohol will change to vapor.