Pure Substances and Mixtures

During a fun science experiment, Hannah and Kai discovered that a ______________ is made up of different kinds of atoms chemically combined. Can you help them figure out what it is?

• 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'.

Scarlett and Aiden are having a debate about their favorite snacks. Scarlett loves Fruit Loops, while Aiden can't get enough of pizza and Skittles. Can you help them figure out if these 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.

During a lively classroom debate, Mason asked, "Is air an element, a compound, or something else entirely?"

• 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.

Charlotte and Avery are on a quest to find a pure substance that cannot be broken down into other substances by chemical or physical means. What magical substance are they looking for? 

• 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.

Which of these is a compound?

• Aluminium (Al)

• Carbon Dioxide (CO2)

• Nitrogen (N)

• Sand

Answer explanation

A compound consists of two or more elements chemically bonded together. Carbon Dioxide (CO2) is a compound made of carbon and oxygen. In contrast, Aluminium (Al) and Nitrogen (N) are elements, and sand is a mixture.

Tags

NGSS.MS-PS1-1

What is an example of a mixture?

• iron

• ice

• soil

• gold

Answer explanation

Soil is a mixture of organic matter, minerals, gases, liquids, and organisms. Unlike pure substances like iron, ice, or gold, which have uniform composition, soil contains various components, making it a clear example of a mixture.