Pure Substances and Mixtures Review

An _______________ is made up of one or more of the same kind of atom chemically combined.

• atom

• element

• molecule

• compound

Answer explanation

An element is defined as a substance made up of one or more of the same kind of atom chemically combined. In contrast, a molecule can consist of different atoms, and a compound is made of different elements.

Tags

NGSS.MS-PS1-1

A ______________ is made up of different kinds of atoms chemically combined.

• element

• compound

• mixture

• molecule

Answer explanation

A compound is formed when different kinds of atoms chemically combine, resulting in a substance with unique properties. In contrast, an element consists of only one type of atom, while mixtures contain multiple substances that are not chemically bonded.

Tags

NGSS.MS-PS1-1

True or False: elements AND compounds are pure substances.

• True

• False

Answer explanation

True. Elements and compounds are both classified as pure substances because they consist of only one type of particle. Elements are made of one kind of atom, while compounds are made of two or more types of atoms chemically bonded.

A ______________ mixture is one that does not have a uniform composition.

• heterogeneous

• homogenous

• pure substance

Answer explanation

A heterogeneous mixture is one that has a non-uniform composition, meaning its components can be easily distinguished. In contrast, a homogeneous mixture has a uniform composition throughout.

A _________________ mixture is one where the substances are evenly spread throughout.

• heterogeneous

• homogeneous

• pure substance

Answer explanation

A homogeneous mixture has a uniform composition, meaning the substances are evenly distributed throughout. In contrast, a heterogeneous mixture has distinct, separate components. Therefore, the correct answer is 'homogeneous'.

Fruit Loops, pizza, and Skittles are examples of ____________________ mixtures.

• heterogeneous

• homogeneous

• pure

Answer explanation

Fruit Loops, pizza, and Skittles are heterogeneous mixtures because they consist of different components that can be easily distinguished and separated, unlike homogeneous mixtures which are uniform throughout.

Which of these is an element?

• Salt (NaCl)

• Water (H20)

• Oxygen (O)

• Carbon Dioxide (CO2)

Answer explanation

Oxygen (O) is an element, which is a pure substance consisting of only one type of atom. In contrast, salt (NaCl), water (H2O), and carbon dioxide (CO2) are compounds made of two or more elements.

Air is:

• An element

• A compound

• A mixture

• None of these

Answer explanation

Air is a mixture because it consists of various gases, primarily nitrogen and oxygen, along with trace amounts of other gases. It is not a pure element or a compound, making 'a mixture' the correct choice.

What is the smallest unit of matter?

• atom

• element

• molecule

• compound

Answer explanation

The smallest unit of matter is an atom. Atoms are the basic building blocks of all substances, while elements are pure substances made of one type of atom, molecules are combinations of atoms, and compounds are made of different types of atoms.

Tags

NGSS.MS-PS1-1

NGSS.MS-PS1-5

A pure substance that cannot be broken down into other substances by chemical or physical means. 

• compound          

• atom

• mixture 

• element

Answer explanation

An element is a pure substance that cannot be broken down into simpler substances by chemical or physical means, unlike compounds and mixtures, which can be separated into their components.