8 P 1 3, 8 P 1 4

One molecule of carbon dioxide (CO₂) combines with one molecule of water (H₂O) to make one molecule of carbonic acid. According to the Law of Conservation of Mass, how many atoms of carbon should be in the carbonic acid?

• 1

• 2

• 3

Tags

NGSS.MS-PS1-1

NGSS.MS-PS1-5

How many copper atoms and how many chlorine atoms are in a molecule of CuCl₂?

• one copper atom, one chlorine atom

• one copper atom, two chlorine atoms

• two copper atoms , one chlorine atom

Tags

NGSS.MS-PS1-1

A chemistry student combines 32 grams of one chemical and an unknown amount of another chemical in a closed system. A chemical reaction occurs and the mass of the products is 114 grams. How much of the unknown chemical was used in the reaction?

• 32 grams

• 82 grams

• 114 grams

Tags

NGSS.MS-PS1-5

What is the importance of a closed container in a chemical reaction?

• to observe the mass before and after the reaction occurs

• to keep any materials from interfering with the reaction

• to observe the loss of mass after the reaction occurs

Tags

NGSS.MS-PS1-5

Which best represents a balanced equation?

• Mg(s) + 2O₂(g) 2MgO(s)

• Mg(s) + O₂(g) 2MgO(s)

• 2Mg(s) + O₂(g) 2MgO(s)

Tags

NGSS.MS-PS1-5

Which best supports the Law of Conservation of Mass?

• Atoms can be rearranged to keep the same mass.

• Atoms can be destroyed to make a new substance.

• Atoms can be rearranged to change their mass.

Tags

NGSS.MS-PS1-5

Which must be true if the number of atoms stays the same regardless of how they are arranged?

• Their total mass must change.

• Their total mass stays the same.

• An open system must have been used.

Tags

NGSS.MS-PS1-5

The compound ammonia is composed of nitrogen and hydrogen atoms. If two atoms of nitrogen completely react with six atoms of hydrogen to form two molecules of ammonia, which best describes the number of hydrogen atoms present in the two molecules of ammonia?

• two hydrogen atoms

• four hydrogen atoms

• six hydrogen atoms

Tags

NGSS.MS-PS1-1

When chemicals react in a closed container, which must be true?

• The mass both before and after the reaction is the same.

• The mass both before and after the reaction is variable.

• The same number of compounds is present both before and after the reaction.

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

Which is the correct way to balance the chemical equation shown below?

Al + O₂ → Al₂O₃

• 2Al + O₂ → Al₂O₃

• 2Al + 3O₂ → Al₂O₃

• 4Al + 3O₂ → Al₂O₃

• 4Al + 3O₂ → 2Al₂O₃

Tags

NGSS.MS-PS1-5