Question

word activity
use the clues to complete the crossword puzzle.
across

1. form or state of matter
2. phase change from liquid to gas at the surface of the liquid
3. change from solid to gas, or from gas to solid

down

1. kind of energy involved in phase change
2. reverse of evaporate
3. substance that is not solid or liquid
4. matter that has a definite volume but takes the shape of its container

questions
a. decide if each statement is true or false. in the space provided, write t or f. if the statement is false, correct the underlined word or words.
___1. the freezing point of a substance is the same as its melting point.
___2. boiling occurs at the surface of a liquid, regardless of temperature.
___3. the fogging - up of a bathroom mirror after you take a hot shower is an example
___4. the higher the air pressure, the lower the boiling point.
___5. sublimation is a phase change from a gas to a liquid, or vice versa.

Explanation:

1. The freezing point and melting point of a substance are the same temperature, just different phase - change directions. So, it's true.
2. Boiling occurs throughout the liquid at its boiling point, while evaporation occurs at the surface of a liquid at any temperature. So, the statement is false and "Boiling" should be replaced with "Evaporation".
3. When you take a hot shower, water vapor in the air condenses on the cooler mirror, which is an example of condensation. So, it's true.
4. The higher the air pressure, the higher the boiling point. So, the statement is false and "lower" should be replaced with "higher".
5. Sublimation is a phase - change from solid to gas or gas to solid, not gas to liquid or vice - versa. So, the statement is false and "gas to a liquid" should be replaced with "solid to a gas".

Answer:

1. T
2. F, Evaporation
3. T
4. F, higher
5. F, solid to a gas