Pure Substances, Mixtures and Compounds

A magnet was placed near a pile that contained both iron and sulfur. The magnet was moved gradually closer to the pile. As it neared the pile, the magnet started attracting small pieces of iron from the pile.

• It is a heterogeneous mixture of iron and sulfur

• It is a homogeneous mixture of iron and sulfur

• It is a compound that contains both iron and sulfur

• It is a compound that can be separated by magnetism

Tags

NGSS.MS-PS2-5

Which of these common substances is a homogeneous mixture?

• Whole milk

• Maple syrup

• Pure water

• Table salt

A material being examined is the same throughout. The material contains carbon and oxygen, chemically combined. What type of material is it?

• Element

• Heterogeneous mixture

• Compound

• Homogeneous mixture

Tags

NGSS.MS-PS1-1

Susie wants to make lemonade on a hot summer day. She mixes lemon juice, water, and sugar in a large container. Which of the following happens as she combines the ingredients?

• The heavier items will not completely dissolve, creating a suspension

• They mix together to form a homogeneous solution

After dinner, Hector demonstrated to his parents a process that he learned in science class that day. He poured a small amount of sugar into a cup of water and then stirred it until the sugar dissolved. Which process did Hector demonstrate?

• How two pure substances can be combined to form a solution

• How substances dissolve in water to produce a pure substance

• How dissolving a substance in water is an example of a chemical reaction

• How to separate components of a solution

In science class, Jonathan added a small amount of sand to a beaker of water. He stirred it vigorously so that all the sand swirled around in the water. Jonathan then claimed to his classmates that he had made a solution. However, his teacher told Jonathan that he was mistaken. Why was the teacher correct?

• The sand will eventually settle to the bottom and will not dissolve in the water

• A chemical reaction did not take place, so a solution was not formed

• Jonathan made a compound, not a mixture

• A solid substance cannot dissolve in water to form a solution

Air contains about 78% nitrogen and 21% oxygen. What can you conclude from this fact?

• Air is a pure substance

• Air is a mixture of at least two gases

• Air consists of components that are chemically joined

• Air consists of different states of matter

Austin is given a mixture of iron filings, sand, and salt. To separate the mixture, Austin uses a magnet, boiling water, and a filter. Which statement is TRUE about the process Austin uses to separate this mixture?

• Austin uses only physical changes to separate the mixture’s components

• Austin uses both physical and chemical changes to separate the mixture’s components

• Austin uses only chemical changes to separate the mixture’s components

• Austin uses neither physical nor chemical changes to separate the mixture’s components

What is the difference between the independent and dependent variables in an experiment?

• The dependent variable is typically found in the first column of a table, and the independent variable is typically found in the second column

• The dependent variable is what the investigator controls, and the independent variable is what happens as a result of this

• The independent variable is always a number, and the dependent variable is never a number

• The independent variable is what you control, and the dependent variable is what changes as a result

Tags

NGSS.MS-PS2-2

Which of these common substances is a homogeneous mixture?

• milk

• Salt water