States of Matter — Answer Key
Part A: Multiple Choice
Circle the best answer for each question.
1. You leave a bowl of water outside on a sunny day and it disappears. What happened?
A) The bowl absorbed the water
B) The water froze and blew away
C) The water evaporated into water vapor
D) The water sank into the bowl
The sun's heat gave the liquid water enough energy for its particles to escape into the air as water vapor. This process is called evaporation, and it is why the bowl ended up empty.
2. Which property do all solids, liquids, and gases share?
A) They all have a definite shape
B) They all have mass and take up space
C) They all flow easily
D) They all can be seen with your eyes
All matter — whether solid, liquid, or gas — has mass and takes up space. Even air, which you cannot see, has mass and fills the space around you.
3. An ice sculpture slowly turns into a puddle at a warm party. Which process is happening?
A) Evaporation
B) Condensation
C) Freezing
D) Melting
The warm air at the party adds heat to the ice sculpture, causing its solid ice particles to break free and become liquid water. This solid-to-liquid change is called melting.
4. Why does a bicycle tire feel firm even though it is filled with air?
A) The air turns into a solid inside the tire
B) Gas particles push outward on the walls of the tire
C) The rubber pulls the air into a solid shape
D) Air does not take up any space inside the tire
The air pumped into the tire is a gas, and its fast-moving particles constantly bounce against the inside walls of the tire. All that pushing outward is what makes the tire feel firm and hold its shape.
Part B: Fill in the Blank
Write the correct answer on each line.
1. When you melt an ice cube and then freeze it again, you can reverse the change.
Melting and freezing are opposite processes, so you can go back and forth between solid and liquid. This makes them reversible changes because no new substance is created.
2. Liquid water has a definite volume but takes the shape of its container.
Liquid water always takes up the same amount of space, but its particles slide around freely, so it flows to match the shape of whatever container holds it.
3. Particles in a gas move in all directions and bounce off each other.
Gas particles have so much energy that they zoom around in every direction — up, down, and sideways — bouncing off each other and the walls of their container.
4. A thermometer measures temperature, which affects the state of matter.
A thermometer measures temperature, which tells you how hot or cold something is. Temperature controls whether a substance stays solid, becomes liquid, or turns into gas.
5. Maple syrup flows slowly because it is a thick liquid.
Maple syrup is a liquid because it flows and takes the shape of its container. It flows slowly because it is thick and sticky, but it is still a liquid just like water.