States of Matter — Answer Key
Part A: Multiple Choice
Circle the best answer for each question.
1. Water in a glass is at room temperature. What state is it in?
A) Solid
B) Liquid
C) Gas
D) Plasma
Water is a liquid at room temperature because it is above freezing but not hot enough to boil.
2. If you put a cup of water in a freezer at -5 degrees C, it will become a:
A) Gas
B) Liquid
C) Solid
D) Cloud
Water freezes into ice, a solid, once the temperature drops below 0 degrees Celsius.
3. If you boil water on a stove at 100 degrees C, it turns into:
A) Solid ice
B) Water vapor (gas)
C) Rock
D) A mirror
Boiling water becomes water vapor, a gas, that rises and spreads into the air.
4. A bar of chocolate is left in a hot car on a sunny day. It will most likely:
A) Stay solid forever
B) Turn into a gas
C) Melt into a liquid
D) Freeze harder
Chocolate melts in warm temperatures, changing from a solid into a liquid puddle.
Part B: Fill in the Blank
Write the correct answer on each line.
1. At 0 degrees Celsius, water changes from liquid to solid.
Below 0 degrees Celsius, water molecules lock together to form solid ice.
2. At 100 degrees Celsius, water changes from liquid into a gas.
At 100 degrees Celsius water molecules speed up and escape as water vapor, a gas.
3. Iron must be heated very hot before it melts into a liquid.
Iron is a solid at room temperature but becomes a liquid at very high heat.
4. Candle wax melts into a liquid, but when it cools it turns back into a solid.
Wax is a solid at room temperature. When cooled, melted wax becomes solid again.
5. Dry ice is so cold it turns straight from a solid into a gas.
Dry ice (frozen carbon dioxide) sublimates, meaning it turns solid to gas without melting.