Unit 2 Review

Which of the following is a metal found on the periodic table?

• Oxygen

• Iron

• Helium

• Chlorine

Answer explanation

Iron is a metal found on the periodic table, while oxygen, helium, and chlorine are non-metals or gases. Therefore, the correct answer is Iron.

Tags

TEKS.SCI.6.6C

DOK Level 1: Recall

What is a common physical property of nonmetals?

• High electrical conductivity

• Brittle when solid

• Malleable

• Shiny appearance

Answer explanation

Nonmetals are typically brittle when solid, meaning they break easily rather than deforming. This contrasts with metals, which are malleable and ductile. Other options like high conductivity and shiny appearance are not common for nonmetals.

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TEKS.SCI.6.6C

DOK Level 1: Recall

Which element is classified as a metalloid?

• Silicon

• Gold

• Neon

• Mercury

Answer explanation

Silicon is classified as a metalloid due to its properties that are intermediate between metals and nonmetals. Gold is a metal, neon is a noble gas, and mercury is a liquid metal, making silicon the correct choice.

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TEKS.SCI.6.6C

DOK Level 1: Recall

Identify the evidence of a chemical change when vinegar is mixed with baking soda.

• Change in color

• Production of a gas

• Formation of a precipitate

• Change in shape

Answer explanation

When vinegar is mixed with baking soda, the production of a gas (carbon dioxide) is observed, indicating a chemical change. This effervescence is a clear sign of a reaction occurring.

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DOK Level 1: Recall

TEKS.SCI.6.6E

Which of the following is an example of a rare Earth element?

• Carbon

• Neodymium

• Sodium

• Zinc

Answer explanation

Neodymium is a rare Earth element, known for its use in strong magnets and various high-tech applications. In contrast, carbon, sodium, and zinc are not classified as rare Earth elements.

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TEKS.SCI.6.6C

DOK Level 1: Recall

What happens to thermal energy during an exothermic chemical reaction?

• It is absorbed

• It is released

• It remains constant

• It decreases

Answer explanation

In an exothermic reaction, thermal energy is released into the surroundings as the reactants transform into products. This release of energy is what characterizes exothermic processes, making 'It is released' the correct choice.

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DOK Level 1: Recall

TEKS.SCI.6.6E

Explain why metals are important in modern life.

• They are used in making glass.

• They are essential for building infrastructure.

• They are used only in jewelry.

• They have no significant use.

Answer explanation

Metals are crucial for building infrastructure, as they provide strength and durability for structures like bridges, buildings, and roads. This makes them essential in modern life, unlike the other options which underestimate their importance.

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TEKS.SCI.6.6C

DOK Level 2: Skill/Concept

Describe a scenario where a color change indicates a chemical reaction.

• Mixing water and sand

• Adding food coloring to water

• Rust forming on iron

• Melting ice

Answer explanation

Rust forming on iron is a clear example of a color change indicating a chemical reaction. The iron reacts with oxygen and moisture, resulting in a reddish-brown rust, demonstrating a transformation in chemical composition.

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TEKS.SCI.6.6E

DOK Level 2: Skill/Concept

How can you identify a metalloid based on its properties?

• It conducts electricity like a metal but is brittle like a nonmetal.

• It is shiny and malleable.

• It is a good insulator.

• It is always a gas at room temperature.

Answer explanation

Metalloids have properties of both metals and nonmetals. They conduct electricity like metals but are brittle like nonmetals, making the first choice the correct identification of a metalloid.

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TEKS.SCI.6.6C

DOK Level 2: Skill/Concept

Predict what happens when a precipitate forms in a chemical reaction.

• The solution becomes clear.

• A solid forms and settles out of the solution.

• The temperature of the solution decreases.

• The solution changes color.

Answer explanation

When a precipitate forms in a chemical reaction, a solid substance is produced that separates from the solution and settles at the bottom, indicating the reaction has occurred. Thus, the correct choice is that a solid forms and settles out.

Tags

TEKS.SCI.6.6E

DOK Level 2: Skill/Concept