Question

1. which example represents a physical change?

a. water evaporating
b. a nail rusting
c. a firework exploding
d. a new substance forming

1. which example represents a chemical change?

a. sugar dissolving in iced tea
b. milk souring
c. cake being sliced
d. a stick of butter melting

Explanation:

Question 8

A physical change is a change in which no new substance is formed, only the physical state or appearance changes.

• Option A: Water evaporating is a phase change (liquid to gas) with no new substance, so it's physical.
• Option B: A nail rusting involves iron reacting with oxygen to form rust (new substance), chemical change.
• Option C: A firework exploding involves chemical reactions producing new substances, chemical change.
• Option D: A new substance forming is the definition of a chemical change.

A chemical change involves the formation of a new substance.

• Option A: Sugar dissolving in iced tea is a physical change (sugar dissolves, no new substance).
• Option B: Milk souring involves bacteria acting on milk to form new substances (like lactic acid), chemical change.
• Option C: Cake being sliced is a physical change (only shape changes, no new substance).
• Option D: Butter melting is a phase change (solid to liquid), physical change.

Answer:

A. Water evaporating

Question 9