Matter and Change Reassessment Activity

Which of the following is an example of a chemical change?

• Sugar stirred into a cup of tea to sweeten it

• Snow melting on a roof

• Cheese being shredded

• Leaves turning color on a tree in autumn

Answer explanation

Leaves turning color in autumn is a chemical change due to the breakdown of chlorophyll and the production of other pigments. The other options involve physical changes, where the substance's chemical composition remains the same.

Tags

NGSS.MS-PS1-2

What is the term for the temperature at which a liquid becomes a solid?

• Boiling point

• Freezing point

• Melting point

• Vaporization point

Answer explanation

The temperature at which a liquid turns into a solid is called the freezing point. This is distinct from the melting point, which is the temperature at which a solid becomes a liquid.

Tags

NGSS.MS-PS1-4

NGSS.MS-PS3-4

Which is an example of a physical property?

• Flammability

• Reactivity with an acid

• Melting point

• Combustibility

Answer explanation

The melting point is a physical property, as it describes a characteristic of a substance without changing its chemical composition. In contrast, flammability, reactivity with an acid, and combustibility are chemical properties.

A substance made up of atoms of two or more different elements joined by chemical bonds.

• Element

• Compound

• Homogeneous mixture

• Heterogeneous mixture

Answer explanation

A compound is defined as a substance formed from two or more different elements chemically bonded together. This distinguishes it from elements, which consist of only one type of atom, and mixtures, which do not involve chemical bonds.

Which of the following mixtures is a homogeneous mixture?

• Apple juice

• Chocolate chip cookies

• Concrete sidewalk

• Chicken noodle soup

Answer explanation

Apple juice is a homogeneous mixture because it has a uniform composition throughout. In contrast, chocolate chip cookies, concrete sidewalk, and chicken noodle soup have distinct components that can be identified separately.

An example of a compound would be...

• Table salt, NaCl

• Hydrogen gas, H₂

• Oxygen gas, O₂

• Gold foil, Au

Answer explanation

Table salt, NaCl, is a compound formed from sodium and chlorine atoms. In contrast, hydrogen gas (H₂), oxygen gas (O₂), and gold foil (Au) are elements or diatomic molecules, not compounds.

Tags

NGSS.MS-PS1-1

Which of the following is an extensive physical property?

• Viscosity

• Color

• Length

• Luster

Answer explanation

Length is an extensive physical property because it depends on the amount of substance present. In contrast, viscosity, color, and luster are intensive properties, which do not change with the quantity of material.

At room temperature, which of the following is typically in a physical state different than that of the others?

• Water

• Milk

• Oxygen

• Coffee

Answer explanation

Oxygen is a gas at room temperature, while water, milk, and coffee are liquids. This makes oxygen the only choice with a different physical state compared to the others.

Classify Salt water as an element (E), compound (C), homogeneous mixture (HO), or heterogeneous mixture (HE).

• E

• C

• HO

• HE

Answer explanation

Salt water is a homogeneous mixture (HO) because it consists of water and salt that are evenly distributed, resulting in a uniform composition throughout. It is not an element or a compound.

Classify Acetone, C₃H₆O as an element (E), compound (C), homogeneous mixture (HO), or heterogeneous mixture (HE).

• E

• C

• HO

• HE

Answer explanation

Acetone, C₃H₆O, is a chemical substance made up of different elements (carbon, hydrogen, and oxygen) bonded together. This qualifies it as a compound (C), not an element, mixture, or homogeneous mixture.

Tags

NGSS.MS-PS1-1