1.2 ENTRY QUIZ Classification of Matter

Which of the following characterizations is incorrect?

• Chicken noodle soup is a heterogeneous mixture.

• Aspirin is composed of 60.0% carbon, 4.5% hydrogen, and 35.5% oxygen by mass, regardless of its source. Aspirin is a compound.

• The tanks that scuba divers use contain nitrogen and oxygen gas. The tanks contain a homogeneous mixture.

• Yellow sulfur consists of molecules that contain eight-membered rings of sulfur atoms. Yellow sulfur is a compound.

• The graphite in lead pencils consists entirely of sheets of carbon atoms. Graphite is a form of an element.

Answer explanation

Yellow sulfur is not a compound; it is an elemental form of sulfur, consisting of cyclic molecules. Therefore, the statement that it is a compound is incorrect.

Tags

NGSS.MS-PS1-1

A certain material has a fixed composition of S and Cl atoms regardless of its source. Which of the following statements about the material is true?

• The material is a homogeneous mixture.

• The material contains atoms of silicon and chlorine.

• The material must contain equal numbers of S and Cl atoms.

• The material is a heterogeneous mixture.

• The material is a compound that contains two elements.

Answer explanation

The problem specifically says fixed composition so there must be equal amounts of S and Cl.

It doesn't say how they're connected so the other statements we can't be sure of.

Tags

NGSS.MS-PS1-1

A gold ingot is best classified as:

• a pure substance

• a solution

• a heterogeneous mixture

Answer explanation

A gold ingot is a pure substance because it consists entirely of gold atoms, with no other elements or compounds mixed in. This distinguishes it from solutions and heterogeneous mixtures, which contain multiple components.

A cup of coffee is best classified as:

• a pure substance

• a solution

• a heterogeneous mixture

Answer explanation

A cup of coffee is best classified as a solution because it consists of coffee solubles dissolved in water, creating a uniform mixture. It is not a pure substance or a heterogeneous mixture.

A wood plank is best classified as:

• a pure substance

• a solution

• a heterogeneous mixture

Answer explanation

A wood plank is made of various components, such as fibers and resins, which do not blend uniformly. This characteristic classifies it as a heterogeneous mixture, as opposed to a pure substance or a solution.

Air and water are both elements.

• True

• False

Answer explanation

Air and water are not elements; they are compounds. Air is a mixture of gases, while water is a compound made of hydrogen and oxygen. Therefore, the statement is false.

Tags

NGSS.MS-PS1-1

All mixtures contain at least one element and one compound

• True

• False

Answer explanation

The statement is false because a mixture can consist of only elements or only compounds, such as air (a mixture of gases) or saltwater (a mixture of salt and water). It does not require both elements and compounds.

Compounds can be decomposed into two or more other substances; elements cannot.

• True

• False

Answer explanation

The statement is true because compounds can be broken down into simpler substances through chemical reactions, while elements are the simplest forms of matter and cannot be decomposed further.

Elements can exist in any of the three states of matter.

• True

• False

Answer explanation

True. Elements can exist in solid, liquid, or gas states depending on temperature and pressure. For example, water (H2O) can be ice (solid), liquid water, or steam (gas).

Tags

NGSS.MS-PS1-4

NGSS.MS-PS3-4

Lemon juice is a pure or nearly pure substance.

• True

• False

Answer explanation

Lemon juice contains water, citric acid, and other compounds, making it a mixture rather than a pure substance. Therefore, the statement is false.