S1 Final Exam Review

Liam and Xzavyer are working on a science project. Why are scientific models important for their project?

• They never change.

• They make understanding harder.

• They help visualize complex concepts.

• They prove theories.

Answer explanation

Scientific models are crucial for projects like Liam and Xzavyer's because they help visualize complex concepts, making it easier to understand and communicate ideas effectively.

Tags

NGSS.MS-LS1-2

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During a chemistry class, Avery is working on an experiment. Which of the following is an example of a safe laboratory procedure?

• Eating or drinking from lab glassware.

• Directly inhaling odors.

• Tying back long hair and loose clothing.

• Touching hot objects with bare hands.

Answer explanation

Tying back long hair and loose clothing is a safe laboratory procedure as it prevents accidents and ensures safety while working with chemicals and equipment. The other options pose safety risks.

During a science class, Anika was asked to identify which of the following is NOT a pure substance. Can you help her?

• Water.

• Milk.

• Oxygen.

• Carbon dioxide.

Answer explanation

Milk is a mixture of water, fats, proteins, and other substances, making it not a pure substance. In contrast, water, oxygen, and carbon dioxide are all pure substances composed of only one type of molecule.

Which particle has the lowest mass?

• Proton.

• Neutron.

• Electron.

• Nucleus.

Answer explanation

The electron has the lowest mass among the given particles. Protons and neutrons are much heavier, while the nucleus is a composite of protons and neutrons, making it even more massive. Thus, the correct answer is the electron.

Jakori is making lemonade and notices that the sugar dissolves completely in the water, making it look like one clear liquid. What type of mixture is this?

• Heterogeneous mixture.

• Homogeneous mixture.

• Compound.

• Element.

Answer explanation

Lemonade is a homogeneous mixture because the sugar dissolves completely in water, resulting in a uniform composition throughout. In contrast, a heterogeneous mixture would have distinct, separate components.

Which of these is a chemical property?

• Flammability.

• Hardness.

• Density.

• Melting point.

Answer explanation

Flammability is a chemical property because it describes how a substance reacts with fire. In contrast, hardness, density, and melting point are physical properties that do not involve chemical changes.

Emma is observing a pot of water on the stove. As the water boils, the temperature of the water:

• Increases.

• Decreases.

• Remains constant.

• Fluctuates unpredictably.

Answer explanation

As water boils, it reaches a temperature of 100°C at standard atmospheric pressure. During boiling, the temperature remains constant while the water changes from liquid to vapor, hence the correct answer is 'Remains constant.'

Tags

NGSS.MS-PS1-4

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What are the building blocks of matter?

• Forces.

• Atoms.

• Magnetic fields.

• Energy.

Answer explanation

The building blocks of matter are atoms, which are the smallest units of elements. They combine to form molecules and ultimately all substances in the universe, making atoms the correct answer.

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What does the formation of an ionic bond involve?

• Sharing electrons.

• Transferring electrons.

• Transferring neutrons.

• Exchanging protons.

Answer explanation

The formation of an ionic bond involves transferring electrons from one atom to another, resulting in the creation of charged ions. This is different from sharing electrons, which occurs in covalent bonds.

Tags

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In the periodic table, as you move from left to right across a period, the number of valence electrons:

• Decreases.

• Increases.

• Stays constant.

• Fluctuates.

Answer explanation

As you move from left to right across a period in the periodic table, each element gains one additional valence electron. Therefore, the number of valence electrons increases.

Tags

NGSS.HS-PS1-1

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