7th grade Science REVIEW 1st Semester

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.

Tags

NGSS.MS-PS1-5

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.

Tags

NGSS.MS-PS1-1

Graphite is a soft, dark material often used as a lubricant. Diamond is often a clear, hard crystal. Which of the following best explains the difference in these materials?

• The arrangement of the atoms of each one

• The elements of which each one is made

• The number of atoms each one is made of

• The size and shape of the individual atoms

Tags

NGSS.MS-PS1-1

Hydrogen and oxygen react to form water. At an atomic level, how do we know that a chemical reaction has occurred?

• Hydrogen molecules are negative, and oxygen positive.

• For every oxygen atom, two hydrogen atoms are needed.

• The hydrogen and oxygen atoms regroup into a new molecule.

• Oxygen atoms are much larger than hydrogen atoms.

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

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.

Tags

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

• A violation of the laws of physics because new mass has been created

Tags

NGSS.MS-PS1-2

Which of the following statements is true?

• 
  Cutting paper is an example of a chemical reaction because a new substance is formed and the process cannot be undone.

• Freezing water is an example of a chemical reaction because a new substance is formed and the process cannot be undone.

• Burning paper is an example of a chemical reaction because a new substance is formed and the process cannot be undone.

• Melting ice is an example of a chemical reaction because a new substance is formed and the process cannot be undone.

Tags

NGSS.MS-PS1-2

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 good evidence that an unknown sample is a pure substance?

• After leaving a liquid to settle, it separates.

• After leaving a liquid to settle, it does not separate.

• 
  Multiple samples of the unknown substance melt at the same temperature.

• 
  Multiple samples of the  unknown substance melt at different temperatures.

Which of the following are accurate headings for each column?

• Column A = Physical Properties; Column B = Chemical Properties

• Column A = Chemical Properties; Column B = Physical Properties

• 
  Column A = Observable Properties; Column B = Non-Observable Properties

• 
  Column A = Non-Observable Properties; Column B = Observable Properties