Physical and Chemical Changes Review

Which example best describes a physical change?

• baking a pie
• burning a candle
• making a paper airplane
• mixing vinegar with baking soda

Brad accidentally left his crayon box in the car on a hot day. Which best explains what happened to his crayons?

• crayons melted; changed from solid to liquid 
• crayons melted; changed from liquid to solid
• crayons evaporated; changed from liquid to solid
• crayons reacted chemically

Which is the best example of a change that can be undone?

• clay put in an oven to harden
• cake batter put in an oven to bake
• chocolate left in a warm car to melt
• wood being burnt

A glass of salt water is put on a windowsill. After several days the water has disappeared, and there is only a film of white crystals left in the bottom. Which best explains what has happened?

• The salt caused the water to dry up.
• The water evaporated and left the salt behind.
• The water and the salt evaporated and left a film behind
• There is no explanation. Magic

Is this a physical or chemical change?

• Physical
• Chemical
• Neither
• Both

Which is an example of a chemical change?

• melting ice to make water
• baking cake batter to make a cake
• putting cheese on bread to make a cheese sandwich
• cutting an orange into slices for a snack

Gwen’s family built a wood fire in the fireplace. The next day, Gwen noticed that there was no wood left in the fireplace, only ashes. Which best explains this?

• Wood is separated from ashes as it burns.
• Wood becomes a new substance as it burns.
• Ashes have the same properties as wood.
• Ashes are the same substance as wood.

Wendy left her bike outside, buried in snow. In the spring, when the snow melted, she found her bike covered in rust. Which best describes the change to the bike?

• It was a chemical change, because the bike was a different color.
• It was a chemical change, because the rubber tires were deflated.
• It was a chemical change, because rust is a new substance on the metal.
• It was a chemical change, because rust can be removed from the metal.

Jonathan is burning wood in a bonfire. What change is occurring during the fire?

• The wood is gaining more mass.
• The wood is changing into a liquid.
• The wood is dissolving into the ground.
• The wood is releasing a gas as smoke.

Is this a physical or chemical change?

• Physical
  
• Chemical
• Neither
• Both