Question

which example best describes a chemical change? a wax melting b an apple turning brown c a piece of paper being cut into small pieces 7. which is a physical change involving an egg? a frying an egg b boiling an egg c breaking an egg 8. jennifer 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? a it was a chemical change, because the bike was a different color. b it was a chemical change, because the rubber tires were deflated. c it was a chemical change, because rust can be removed from the metal. d it was a chemical change, because rust is a new substance on the metal. 9. which is an example of a change that will produce a new substance? a a piece of wood is burned and turns to ash. b a glass jar breaks into smaller shards of glass. c a puddle of water evaporates into water vapor. d a piece of paper gets wet and is shredded apart. 10. which best explains what happens to the inside of an egg when it is boiled? a the liquid becomes solid. b the solid becomes a gas. c the solid becomes a liquid. d the liquid becomes a gas.

Explanation:

1. Chemical changes result in new substances. An apple turning brown is due to oxidation, a chemical reaction creating new compounds. Wax melting is a physical state - change, and cutting paper is a physical change in shape.
2. Physical changes don't create new substances. Breaking an egg only changes its physical state without altering its chemical composition. Frying and boiling eggs are chemical changes due to protein - denaturation.
3. Rust on a bike is a new substance (iron oxide) formed by a chemical reaction between iron, oxygen, and water, so it's a chemical change.
4. Burning wood produces ash, a new substance, which is a chemical change. Breaking a glass jar, water evaporation, and shredding wet paper are physical changes.
5. When an egg is boiled, the liquid egg white and yolk proteins denature and become solid.

Answer:

1. B. an apple turning brown
2. C. breaking an egg
3. D. It was a chemical change, because rust is a new substance on the metal.
4. A. A piece of wood is burned and turns to ash.
5. A. The liquid becomes solid.