Chemical Reactions and Equations Review

Which of the following would indicate that a chemical reaction has occurred?

• A new element has been created

• A different substance has formed

• The total mass has either increased OR decreased

• The total number of elements has either increased OR decreased

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

Which would indicate a chemical equation is balanced?

• If the number of atoms in the reactants is the same as the number of atoms in the products

• If the atoms have ionic OR covalent bonds

• If the atoms have full valence shells

• If the total energy has remained the same

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

BEFORE the equation is balanced, how many Hydrogen atoms are present on the reactant side?

• 6

• 2

• 12

• 8

Tags

NGSS.MS-PS1-1

NGSS.MS-PS1-2

NGSS.MS-PS1-5

Why does the number of Carbon atoms need to be the same on both sides of the reaction?

• In a chemical reaction, no new atoms can be made

• Because the number of Oxygen atoms must be balanced with the number of Carbon and Hydrogen atoms

• Because the coefficients and the subscripts need to be equal

• It does NOT need to be the same

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

How many sulfur atoms are present in this molecule?

• 4

• 3

• 12

• 1

Tags

NGSS.MS-PS1-1

In the molecule below, which of the following choices is a subscript? (Select all that apply)

• 3

• 2

• 4

• SO

Tags

NGSS.MS-PS1-1

Which of the following follows the Law of Conservation of Mass?

• CH₄ + 2 O₂ → 2CO₂ + 2 H₂O

• 2 CH₄ + 2 O₂ → CO₂ + 4 H₂O

• CH₄ + 2 O₂ → CO₂ + 2 H₂O

• All the above

In a chemical reaction, ________________________ are changed into _______________________.

• Reactants; Products

• Electrons; Molecules/Compounds

• Coefficients; Subscripts

• Original Elements; New Elements

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

Which of the following type of chemical reaction is only possible with Oxygen as a reactant?

• Synthesis

• Combustion

• Decomposition

• Physical property

Which of the following type of chemical reaction builds larger compounds from smaller ones?

• Synthesis

• Combustion

• Decomposition

• Exothermic