What is a mixture?

• A. A combination of substances that keep their original properties

• B. A new substance formed from two materials

• C. A liquid that turns into a solid

• D. A substance that cannot be separated

Answer explanation

A mixture is defined as a combination of substances that retain their original properties, making option A the correct choice. In contrast, option B describes a compound, while C and D refer to different states and types of matter.

Which tool can best separate iron filings from sand?

• Strainer

• Magnet

• Filter paper

• Beaker

Answer explanation

A magnet is the best tool to separate iron filings from sand because it attracts the iron filings, allowing for easy removal, while the sand remains unaffected.

What happens to substances in a mixture?

• They lose their properties

• They form a new substance

• They maintain their original properties

• They react chemically

Answer explanation

In a mixture, substances retain their original properties, meaning they do not lose their characteristics or form new substances. This is why the correct answer is that they maintain their original properties.

Which of the following is an example of a mixture?

• A. Salt and water

• B. Burning wood

• C. Baking a cake

• D. Rust forming on a nail

Answer explanation

A mixture consists of two or more substances that are not chemically combined. Salt and water form a solution, which is a type of mixture. In contrast, burning wood, baking a cake, and rust formation involve chemical changes.

What happens when you mix sand and water?

• The sand dissolves

• The sand remains separate

• The sand turns into a gas

• The sand changes color

Answer explanation

When sand and water are mixed, the sand does not dissolve; instead, it remains separate and settles at the bottom. This is because sand is a solid and does not change its state in water.

Tags

NGSS.5-PS1-4

Which statement best describes why salt and water form a solution, while sand and water form a mixture?

• A. Salt dissolves in water, but sand does not

• B. Both salt and sand dissolve in water

• C. Sand reacts chemically with water

• D. Sand is less dense than salt

Answer explanation

A. Salt dissolves in water, forming a solution, while sand does not dissolve and remains as separate particles, creating a mixture. This key difference explains why they behave differently in water.

Which physical property allows a filter to separate sand from water?

• Size of particles

• Solubility

• Density

• Magnetism

Answer explanation

The filter separates sand from water based on the size of particles. Sand particles are larger than water molecules, allowing water to pass through while trapping the sand.

Which method is best for separating salt from water?

• Straining

• Using a magnet

• Evaporation

• Filtration

Answer explanation

Evaporation is the best method for separating salt from water because it allows the water to turn into vapor, leaving the salt behind. Straining and filtration do not work since salt dissolves in water, and a magnet cannot attract salt.

Which two substances would NOT form a solution when mixed? (Select two correct answers.)

• A. Sugar and water

• B. Oil and water

• C. Sand and water

• D. Salt and water

Answer explanation

Oil and water do not mix due to differences in polarity, making them immiscible. Similarly, sand does not dissolve in water, resulting in a mixture rather than a solution. Thus, B and C are correct.

A student mixes iron filings, sand, and salt. What should be done first to separate the mixture?

• Use a filter

• Add water

• Use a magnet

• Heat the mixture

Answer explanation

To separate the mixture, the first step is to use a magnet. Iron filings are magnetic, so they will be attracted to the magnet, allowing you to easily separate them from the non-magnetic sand and salt.