Question

answer in 1 - 2 sentences each.

1. what happens to the motion of particles when heat is added to a solid?
2. why does condensation form on the outside of a cold glass?
3. explain how evaporation helps cool your body when you sweat.
4. give one example of sublimation that you can observe in daily life.
5. why is freezing considered the opposite of melting?

Explanation:

1. When heat is added to a solid, the particles gain energy and their motion increases.
2. Condensation forms on the outside of a cold glass because warm, moist air comes into contact with the cold surface, causing the water vapor in the air to lose energy and change from a gas to a liquid.
3. Evaporation helps cool your body when you sweat because as the sweat (a liquid) evaporates (changes to a gas), it absorbs heat from your body.
4. One example of sublimation in daily life is dry ice (solid carbon dioxide) changing directly to gas.
5. Freezing is considered the opposite of melting because melting is a solid changing to a liquid (gaining energy) and freezing is a liquid changing to a solid (losing energy).

Answer:

1. Particles gain energy and motion increases.
2. Warm moist air cools on cold glass, water vapor condenses.
3. Sweat evaporation absorbs body heat.
4. Dry ice sublimating.
5. Melting: solid→liquid (gain energy); freezing: liquid→solid (lose energy).