Question

the table below records observations made when investigating interactions between 4 substances.

substances	observation
b and c	substance c overflows out of the test tube and substance b stays at the bottom of the test tube
a and c	bubbles rise from the bottom of the test tube, and the color of the substances change from clear to yellowish.
b and d	a pop sound and bright light are released.
c and d	substance d dissolves in substance c.

1. which interactions between substances are chemical changes? select all that apply.

• a and b
• b and c
• a and c
• b and d
• c and d

1. which of the following are chemical changes? select all that apply.

a. dissolving sugar
b. burning wood
c. firework exploding
d. water freezing
e. carving wood

Explanation:

Step1: Identify chemical changes (Q10)

Chemical changes involve new substances; physical changes do not.

• A and B: Bubbles (gas) + temp change → chemical.
• B and C: Layer separation (density) → physical.
• A and C: Bubbles + color change → chemical.
• B and D: Pop (gas) + light → chemical.
• C and D: Dissolving → physical.

Step2: Identify chemical changes (Q11)

• A: Dissolving sugar (no new substance) → physical.
• B: Burning wood (ash/gas) → chemical.
• C: Firework exploding (gas/light) → chemical.
• D: Water freezing (state change) → physical.
• E: Carving wood (shape change) → physical.

Answer:

1. A and B, A and C, B and D
2. B. Burning wood, C. Firework exploding