States of Matter — Answer Key
Part A: Fix the Sentence
Each sentence has an error. Rewrite it correctly on the line.
1. Fix the sentence:
Freezing changes a gas into a solid.
Corrected: Freezing changes a liquid into a solid.
Freezing happens when a liquid gets cold enough to become a solid. For example, liquid water freezes into solid ice — it does not skip from gas to solid.
2. Fix the sentence:
A table is a liquid because it is heavy.
Corrected: A table is a solid because it has a definite shape.
A table is a solid because it holds its own shape without a container. Being heavy does not make something a liquid — what matters is whether it keeps a definite shape.
3. Fix the sentence:
Cooling a liquid always turns it into a gas.
Corrected: Cooling a liquid can turn it into a solid.
Cooling removes heat from a liquid, which slows its particles down until they lock into place as a solid. Heating — not cooling — is what turns a liquid into a gas.
Part B: Fill in the Blank
Write the missing word or number on each line.
1. When you heat chocolate, it melts from a solid to a liquid.
Heat causes the solid chocolate particles to move faster and slide apart, so the chocolate melts and becomes a liquid you can pour.
2. The air we breathe is made of several different gases.
Air is a mixture of gases such as nitrogen and oxygen. You cannot see these gases, but they are all around you and you breathe them in every day.
3. An ice pop left outside on a hot day will melt.
The heat from the sun warms the frozen ice pop and causes it to melt, changing it from a solid back into a liquid.
4. Particles in a gas move faster than particles in a solid.
Gas particles zoom around freely in every direction, while solid particles only vibrate in place. That extra energy is why gases spread out and solids keep their shape.
Part C: True or False?
Read each statement. Circle True or False.
1. Water can exist as a solid, a liquid, or a gas.
True False
Water is special because it can be found in all three states: ice (solid), liquid water, and steam or water vapor (gas). Temperature determines which state it is in.
2. A liquid keeps its own shape without a container.
True False
A liquid does not keep its own shape — it flows and takes the shape of whatever holds it. If you spill water on a table, it spreads out because it has no fixed shape.
3. Adding heat to a substance can change its state of matter.
True False
Heat gives particles more energy so they move faster and spread apart. That is why adding heat can melt a solid into a liquid or boil a liquid into a gas.