Pure Substances and Mixtures

During a science experiment, Daniel and Arjun mixed different substances. Which substance can be identified as a homogeneous mixture?

• salt water

• salad

• chocolate chip cookie

• peanut butter sandwich

Which picture represents a 2D model of a mixture of two elements?

• A

• B

• C

• D

• E

Tags

NGSS.MS-PS1-1

Which picture represents a 2D model of a mixture of two compounds?

• A

• B

• C

• D

• E

A student has a sample of a solid dissolved in a liquid. The task is to separate the mixture into its pure components. What question is best asked in the design of the experiment to determine how to separate the components?

• Can the solution be filtered using filter paper and a funnel?

• Can the solid be physically removed with forceps or a small manipulative?

• Will the solvent evaporate at a different temperature than the solute in a distillation procedure?

• Will the solid form a distinct layer on the bottom of the mixture when the mixture is not in motion?

Hydrogen and oxygen combine to form water, as shown in the diagram below. Based on the diagram, which statement best represents the formation of water from hydrogen and oxygen?

• A mixture has formed from hydrogen and oxygen physically combined.

• A mixture has formed from hydrogen and oxygen chemically combined.

• A pure substance has formed from the hydrogen and oxygen physically combining.

• A pure substance has formed from the hydrogen and oxygen chemically combining.

Tags

NGSS.MS-PS1-1

NGSS.MS-PS1-2

NGSS.MS-PS1-5

Ms. Roberts asked Tim to put the label 'compound' on the correct jar in the picture. Which of the four substances is a compound?

• chlorine

• nitrogen

• sodium

• water

Tags

NGSS.MS-PS1-1

How does a compound differ from a mixture?

• Compounds have two or more components.

• Each substance in a compound loses its characteristic properties.

• Compounds are commonly found in nature.

• Solids, liquids, and gases can form compounds.

Which of the following sentences best describes table salt, NaCl?

• Table salt is a compound made from two elements.

• Table salt is a mixture made from two elements.

• Table salt is an element made from two mixtures.

• Table salt is an alloy made from a metal and a nonmetal.

Tags

NGSS.MS-PS1-1

When elements form mixtures,

• the elements keep their original properties.

• the elements react to form a new substance with new properties.

• the elements combine in a specific mass ratio.

• the elements always change their physical state.

Tags

NGSS.MS-PS1-1

Which models represent mixtures?

• Model A & Model B

• Model A & Model D

• Model B & Model C

• Model C & Model D