Question

1. classify each of the following as a chemical change or a physical change. a. plastic drink bottles are burned in an incinerator to generate electricity. b. digesting a cereal bar. c. water in a rain puddle evaporates. d. slicing a tomato for a sandwich. e. plastic drink bottles are recycled to make fiberfill for ski jackets.

Explanation:

To solve this, we recall: A physical change doesn’t alter the substance’s chemical identity (e.g., phase changes, cutting). A chemical change forms new substances (e.g., burning, digestion).

Part (a)

Burning plastic involves combustion (reaction with oxygen), forming new substances (like CO₂, ash).

Answer:

** Chemical change

Part (b)

Digestion breaks down food (e.g., carbohydrates to glucose) via chemical reactions (enzymes, metabolism). New substances form.