3.Kyla tests four solutions using litmus paper. When she accidentally spills one solution, the red paper turns blue. What can Kyla conclude about the spilled solution?
C. It is basic.
14. A plastic spoon turns black and gives off a burnt odor when exposed to flame. What type of change happened?
C. Physical change due to heat
6. Solid air freshener slowly disappears in a warm room. What happens to its molecules?
C. They lose energy and form a liquid.
1. Jana uses marbles of different colors and sizes to represent atoms from different elements. How can she best model how compounds form in nature?
B. Combine marbles of different colors to represent elements bonding to form a compound.
13. During an experiment, a wax candle melts and then solidifies again after cooling. What kind of change occurred?
A. Irreversible chemical change
11. Two substances with total mass of 12 g react to form bubbles. After the reaction, the beaker shows 9 g of mass. What best explains this result?
A. Some matter was destroyed.
5. Several groups test the pH of water samples around the campus. Which conclusion would be scientifically valid?
B. Differences in readings suggest nearby materials affect pH.
2. Marco examines an unknown milky liquid that looks evenly mixed. When he filters it, small solid bits remain in the filter paper. What evidence shows the substance is not pure?
C. The filter left behind small solid pieces.
19. A sealed container has 5 g of liquid and 1 g of gas. After a reaction, it contains only gas. What is the total mass?
C. 6 g
16. When vinegar reacts with baking soda, bubbles form. What does this show?
B. A new gas formed during a chemical change.
15. After burning dry leaves, the ashes weigh less than the original leaves. How does this still follow the Law of Conservation of Mass?
A. Some mass turned into smoke and gases that escaped.
10. A metal reacts slowly with cool acid, but faster with warm acid. What explains this?
A. Warm acid increases particle collisions.
17. What happens to the rate of reaction when the temperature increases?
B. The reaction stops completely.
20. Which statement about matter is always true according to the law of conservation?
B. Mass is always destroyed during reactions.
8. Which situation best shows a physical change?
C. Cutting a piece of wood.
7. Liam fries an egg and then stirs sugar into coffee. Which statements describe the changes?
D. Frying an egg is physical; dissolving sugar is chemical.
4. Different mixtures of bronze melt at different temperatures. Why does this happen?
B. They contain different amounts of copper and tin.
12. Which correctly identifies the samples?
A. Oxygen gas – element Carbon dioxide – compound Air – mixture
18. Which observation best shows that a chemical change occurred?
B. Sugar dissolving in water
9. Which example best supports the Law of Conservation of Mass?
A. Melting 10 g of ice into 10 g of water.
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