8th Grade Unit 2 Review

Which of the following is true about how hydrogen and oxygen can combine to form molecules?

• Hydrogen and oxygen can combine in many ways to form different molecules.

• Two atoms of hydrogen are always required to bond with two atoms of oxygen.

• When oxygen combines with hydrogen to make a molecule, water will always be produced.

• Molecules composed of hydrogen and oxygen must have at least four atoms.

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NGSS.MS-PS1-1

Which of the following best explains the relationship between molecules and atoms?

• Atoms are molecules that have a charge.

• Atoms have smaller parts, called molecules.

• Molecules are made up of two or more atoms.

• Molecules are atoms that have no mass.

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NGSS.MS-PS1-1

Which of the following is the best description of the results of a chemical reaction?

• A new substance with different properties is formed.

• The substance seems to disappear after dissolving in water.

• The substance changes from liquid to solid at a low temperature.

• The reaction can be reversed to get back the original substance.

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NGSS.MS-PS1-2

Rust forming on a piece of iron is an example of which of the following:

• A physical change because the process can be reversed

• The natural process of decay as metallic ions age

• A chemical change because oxygen atoms from the atmosphere bonded with the iron atoms

Tags

NGSS.MS-PS1-2

During a chemical reaction, substances (called reactants) are combined to form new substances (called products). Which of the following accurately describes the reactants and the products of a chemical reaction?

• The products contain a different number of atoms than the reactants but have the same properties.

• The number of atoms and the properties are the same in the reactants and the products.

• The products contain the same number of atoms as the reactants but have different properties.

• The number of atoms and the properties are different in the reactants and the products.

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NGSS.MS-PS1-2

NGSS.MS-PS1-5

A student finds the mass and volume of four mystery liquids. The data is provided. The student knows that the density of water is 1 g/mL. Which of the four mystery liquids can be correctly identified as water?

• W

• X

• Y

• Z

Tags

NGSS.MS-PS1-2

Which of the following is NOT an indicator of a chemical reaction?

• A phase change

• A temperature change

• A color change

• A gas being created

Tags

NGSS.MS-PS1-2

A sample known to be one of the four listed in the table was heated to a temperature of 350 ℃ but remained a solid. The sample was found to have a density greater than 6 g/cm³ and to be a good conductor of electricity. Burning the sample produced a blue flame. Based on this information, what is the identity of this sample?

• Zinc

• Lead

• Tin

• Iron

Tags

NGSS.MS-PS1-2

Which of the following is true regarding the atoms involved in a chemical reaction?

• The same number of each type of atom will always be present before and after a chemical reaction takes place.

• Some of the atoms present before the reaction will always be lost during a chemical reaction.

• Some of the atoms will always be changed into a different type of atom by a chemical reaction.

• Some of the atoms will always be changed into a different type of atom by a chemical reaction.

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

In a chemical reaction known as decomposition, carbonic acid breaks down into water, and what other compound?

• 
• 
• 
• 

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5