Chemistry Unit Test - 2025

A student develops a model of methane (CH₄), as shown. Use the drop-down menus to identify the substance in the model as an element or a compound. The model is a(n)​ (a)   because it shows​ (b)   one type of atom and is​ (c)   by a chemical bond.

• compound
• element
• more than
• only
• held together
• not held together

Tags

NGSS.MS-PS1-1

The picture shows an isotope of an element. Based on the information in the periodic table, which element is shown in the picture?

• • boron (B)

• • lithium (Li)

• • carbon (C)

• • helium (He)

Tags

NGSS.MS-PS1-1

Liam explores the decomposition of water. He attaches a battery to the ends of two pencils sharpened at both ends, and places the other ends of the pencils in a beaker of water. His set up is shown below.
Liam knows that some of the bubbles in his experiment must be oxygen. He draws an atomic model of the element oxygen. What does he include in his drawing? Select all that apply.

• eight protons in the nucleus

• sixteen protons in the nucleus

• eight electrons outside of the nucleus

• sixteen electrons outside of the nucleus

• eight neutrons in the nucleus

Tags

NGSS.MS-PS1-1

Darnell draws a picture of a nitrogen atom. He draws a small circle to represent the nucleus and draws dots around the circle to represent the electrons. How many dots does he draw?

• 5 dots

• 7 dots

• 14 dots

• 16 dots

Tags

NGSS.MS-PS1-1

Bernice draws an oxygen atom. She draws a small circle for the nucleus. Inside of the circle, she draws plus signs for protons and dots for neutrons. Around the nucleus she uses minus signs to represent electrons. Which statements are true about her drawing? Select ALL that apply.

• There are eight protons in the nucleus.

• There are sixteen protons in the nucleus.

• There are eight neutrons in the nucleus.

• There are sixteen neutrons in the nucleus.

• There are sixteen electrons in her drawing.

Tags

NGSS.MS-PS1-1

Using information from the periodic table, which diagram shows a correct model for an atom of neon?

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Tags

NGSS.MS-PS1-1

Pure Substances and Mixtures

Two categories of substances are pure substances and mixtures.

Pure substances have a constant chemical composition and chemical properties. Elements and compounds are examples of pure substances. Elements consist of one or more of one type of atom and are not chemically bonded. Compounds consist of two or more types of elements that are held together with a chemical bond.

Mixtures contain two or more different substances that are not held together with a chemical bond. Two types of mixtures are homogeneous and heterogeneous mixtures. Homogeneous mixtures have a uniform composition throughout the mixture, while heterogenous mixtures do not.

A student develops models of pure substances and mixtures using different colors of balls and plastic sticks. A key for each element and chemical bond is shown.

A model of a substance in a container is shown. Which best identifies the type of substance in the container?

• element

• compound

• heterogeneous mixture

• homogeneous mixture

Tags

NGSS.MS-PS1-1

Pure Substances and Mixtures

Two categories of substances are pure substances and mixtures.

Pure substances have a constant chemical composition and chemical properties. Elements and compounds are examples of pure substances. Elements consist of one or more of one type of atom and are not chemically bonded. Compounds consist of two or more types of elements that are held together with a chemical bond.

Mixtures contain two or more different substances that are not held together with a chemical bond. Two types of mixtures are homogeneous and heterogeneous mixtures. Homogeneous mixtures have a uniform composition throughout the mixture, while heterogenous mixtures do not.

A student develops models of pure substances and mixtures using different colors of balls and plastic sticks. A key for each element and chemical bond is shown.

Which description of the substance best supports the choice from Part A?

• The substance consists of one type of atom.

• All substances in the container are chemically bonded.

• There is a uniform composition throughout.

• There is not a uniform composition throughout.

Tags

NGSS.MS-PS1-1

Pure Substances and Mixtures

Two categories of substances are pure substances and mixtures.

Pure substances have a constant chemical composition and chemical properties. Elements and compounds are examples of pure substances. Elements consist of one or more of one type of atom and are not chemically bonded. Compounds consist of two or more types of elements that are held together with a chemical bond.

Mixtures contain two or more different substances that are not held together with a chemical bond. Two types of mixtures are homogeneous and heterogeneous mixtures. Homogeneous mixtures have a uniform composition throughout the mixture, while heterogenous mixtures do not.

A student develops models of pure substances and mixtures using different colors of balls and plastic sticks. A key for each element and chemical bond is shown.

Which two are examples of elements?

• Hydrochloric Acid  (HCl)

• nitrogen (N)

• water (H₂O)

• hydrogen (H)

• ammonia (NH₃)

Tags

NGSS.MS-PS1-1

​ ​ Which 2 are pure substances?

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Tags

NGSS.MS-PS1-1