8th Grade Sci. End of Matter Unit Review

If you were looking at salad dressing, and you notice oil and vinegar have separated, and their are herbs SUSPENDED in the salad dressing, how would the model help you classify the substance?

• If the oily layer can be physically removed from the vinegar, it must be a mixture. If the herbs can be physically removed, it must be a solution.

• If the oily layer can be physically removed from the vinegar, it must be a pure substance. If the herbs can be physically removed, it must be a compound.

• If the oily layer can be physically removed from the vinegar, it must be a mixture. If the herbs can be visibly seen in the midst of the dressing, it must be a suspension.

• If the oily layer can be physically removed from the vinegar, it must be a pure substance. If the herbs can be physically removed, it must be elemental.

If you had a sample of ocean water, what steps could you take to classify ocean water as a suspension, solution, element or compound?

• Evaporate the water. If salt is left behind, the sample is a mixture that can be defined as a solution.

• Let the sample settle. If the salt settles to the bottom, it is a mixture that is classified as a solution.

• Observe the diffraction of light as it moved through the sample. If light does not scatter, it is a pure substance that is elemental.

• Examine the pH of the sample. If the pH is exactly neutral, it is a pure substance that is a compound.

What material is a pure substance from these choices?

• Alloy (mixture of two metals)

• Compound

• Mixture

• Solution (Homogeneous Mixture)

When two or more substances combine, but each substance keeps its own properties and identity, (like a strawberry banana smoothie) what is this new substance classified as?

• element

• compound

• mixture

• homogeneous substance

Compare the box on the left containing the reactants in a chemical reaction. 

Which box on the right, correctly represents the products according to the Law of Conservation of Mass?

• A

• B

• C

• D

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The Law of Conservation of matter states that:

• The mass of the reactants must equal the mass of the products

• The mass of the reactants is less than the mass of the products

• The mass of the products is always greater than the mass of the reactants

• Matter and mass are lost when atoms combine

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NGSS.MS-PS1-5

15g of salt is dissolved into 115g of water. What is the total mass of the solution?

• 20g

• 40g

• 100g

• 130g

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NGSS.MS-PS1-2

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If a sample substance demonstrates properties such as having a high melting and boiling point, conducting electricity, it is shiny, solid at room temperature, and can be hammered flat, it must be classified as a:

• Nonmetal

• Gas

• Metal

• Halogen

You forget to bring your bike in and it rains overnight. The next morning, you notice that your bike chain is rougher and has brownish and yellowish discoloration. This rusting process means:

• A chemical change has occured

• A physical change has occured

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NGSS.MS-PS1-2

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Where would you place the following property on the Venn Diagram: Melting point

• A

• B

• C

• D

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