Unit 3 Test Study Guide: Matter and Its Changes

The Statue of Liberty's corrosion is made of copper sulfate and copper carbonate. Which of the following statements describes the motion of the molecules?

• The molecules of the statue are never moving.

• The molecules of the statue are always moving.

• The molecules of the statue move only when the sun warms the surface.

• The statue of the statute move only when people are looking at it

Answer explanation

The molecules of the Statue of Liberty are always moving due to thermal energy, even in solid materials. This constant motion is a fundamental property of matter, making the correct choice "The molecules of the statue are always moving."

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NGSS.MS-PS3-1

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Lucifer left a cup of coffee at 67°C next to a glass of pineapple nectar at 7°C in a 21°C room overnight. The temperature of the two beverages the next day will be about

• 70°F

• 27°C

• 21°C

• 37°C

Answer explanation

Overnight, both beverages will reach thermal equilibrium with the room temperature of 21°C. Thus, the final temperature of the coffee and pineapple nectar will be about 21°C.

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NGSS.MS-PS1-4

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Directions: Drag the answers to the correct boxes. The pictures below show the arrangement of particles in three phases of matter. Match the picture with the correct phase of matter.

• Solid

• 
• Liquid

• 
• Gas

• 

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Aquaman put a pot of water over a campfire and heated it. He took the temperature of the water as soon as it started to boil. The thermometer showed 100°C. Aquaman turned the heat up and the water continued to boil for 5 minutes. He then took the temperature of the boiling water again. What does the thermometer show?

• Less than 100°C; as the water boils away, the boiling point drops.

• A sense of betrayal to the people of the water

• Exactly 100°C; water boils at a constant temperature.

• Greater than 100°C; James increased the heat applied to the boiling water.

Answer explanation

The thermometer will show exactly 100°C because water boils at a constant temperature under normal atmospheric pressure. Increasing the heat does not raise the boiling point; it remains the same as long as the water is boiling.

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NGSS.MS-PS1-4

A mercury thermometer has a toxic metal liquid inside it. The level of the liquid metal rises when the thermometer is placed in hot water. Why does the level of the liquid rise?

• Water molecules are pushed into the thermometer.

• Heat molecules push the molecules of the liquid upward.

• Heat causes the molecules of the liquid to go farther apart.

• The molecules of the liquid break down into atoms and take up more space.

Answer explanation

The correct answer is that heat causes the molecules of the liquid to go farther apart. As the temperature increases, the kinetic energy of the liquid's molecules increases, leading them to expand and rise in the thermometer.

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NGSS.MS-PS1-4

When ice melts, a(n) ---

• chemical change rearranges the molecules of water

• electrical change prevents current flow through the resulting solution

• physical change rearranges the molecules to a new state of matter

• thermal change releases thermal energy to the environment

Answer explanation

When ice melts, it undergoes a physical change, transitioning from solid to liquid. This process rearranges the molecules of water into a new state of matter without altering their chemical structure.

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Which of the following conclusions can be made based on the results of the experiments?

• Chemical changes occurred in both experiments.

• Physical changes occurred in both experiments.

• A chemical change occurred in experiment 1, and a physical change occurred in experiment 2.

• A physical change occurred in experiment 1, and a chemical change occurred in experiment 2.

Answer explanation

The experiments resulted in chemical changes, indicating that new substances were formed in both cases. Therefore, the conclusion that chemical changes occurred in both experiments is correct.

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NGSS.MS-PS1-2

A chef mixes two different liquids together. After mixing the liquids, a solid substance forms that cannot be turned back into the starting liquids. The chef claims that a chemical reaction occurred. Why is the chef correct?

• Because a solid substance is always formed during a chemical reaction

• Because a new substance is always formed during a chemical reaction

• Because a chemical reaction always occurs when two substances are mixed together

• Because the products of a chemical reaction can never be turned back into the starting substances

Answer explanation

The correct choice is that a new substance is always formed during a chemical reaction. In this case, the formation of a solid indicates a chemical change, resulting in a substance that differs from the original liquids.

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NGSS.MS-PS1-2

Drag the answers to the correct boxes. Label each example below with the correct type of change taking place.

• Endothermic Chemical Change

• 
• Exothermic Chemical Change

• 
• Physical Change

• 

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Directions: Select the correct answers. The pairs of elements below often form chemical bonds. Select which pairs of elements are likely to form ionic bonds.

• Na and F

• N and O

• H and C

• Mg and Cl

Answer explanation

Ionic bonds typically form between metals and nonmetals. Na (a metal) and F (a nonmetal) can transfer electrons, forming NaF. Similarly, Mg (a metal) and Cl (a nonmetal) can form MgCl2. The other pairs are covalent.

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NGSS.MS-PS1-1