8.6E Mastery Bell Ringer

A student burns a piece of magnesium in a closed system and measures the mass before and after the reaction. What should they observe?

• The mass decreases because some magnesium turns into energy.

• The mass remains the same because matter is neither created nor destroyed.

• The mass increases because magnesium gains energy from the reaction.

• The mass fluctuates due to energy transfer.

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

Which statement best describes how atoms rearrange in a chemical reaction?

• Some atoms disappear while new ones are created.

• The number of atoms in the reactants is different from the products.

• Atoms are rearranged into different compounds, but none are lost or gained.

• The reaction creates more mass than it started with.

Tags

NGSS.MS-PS1-5

Which equation correctly demonstrates the Law of Conservation of Mass?

• CH₄ + O₂ → CO₂ + 2H₂O

• H₂ + Cl₂ → 2HCl

• NaCl + H₂O → Na + Cl₂ + O₂

• 2Fe₂O₃ → Fe + O₂

Tags

NGSS.MS-PS1-5

A student writes a chemical equation but notices the reactants and products have different numbers of atoms. What should they do?

• Add or remove atoms to balance the equation.

• Rewrite the equation using different elements.

• Adjust coefficients to ensure the same number of each atom appears on both sides.

• Ignore the imbalance since some mass is always lost.

Tags

NGSS.MS-PS1-5

In the process of photosynthesis, plants convert carbon dioxide and water into glucose and oxygen. Which statement about mass conservation in this reaction is true?

• The total mass of carbon dioxide and water is greater than the mass of glucose and oxygen.

• The mass of reactants equals the mass of products due to conservation of mass.

• Some mass is lost as energy in the reaction.

• Plants create new mass in the form of glucose.

Tags

NGSS.MS-LS1-6

NGSS.MS-PS1-5

Which of the following best explains why the mass of a burning candle appears to decrease over time?

• The wax is converted into light and heat energy.

• The wax undergoes a chemical reaction, releasing gases into the air.

• The wax disappears due to melting.

• The wax turns into new solid matter.

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

Which of these represents a correctly balanced chemical equation?

• H₂ + O₂ → H₂O

• 2H₂ + O₂ → 2H₂O

• H₂ + O₂ → 2H₂O

• 2H₂ + 2O₂ → 2H₂O

Tags

NGSS.MS-PS1-5

A scientist investigates a reaction between iron (Fe) and oxygen (O₂) that produces iron oxide (Fe₂O₃). If the scientist starts with 112 g of iron and 48 g of oxygen, what will be the total mass of iron oxide?

• 112 g

• 48 g

• 160 g

• 224 g

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

A student is given the equation Na + Cl₂ → NaCl. After measuring the reactants and products, they find that the mass of NaCl is slightly less than expected. What is the most likely explanation?

• Conservation of mass was violated.

• Some chlorine gas escaped before it reacted.

• New atoms were created.

• The reaction absorbed matter from the air.

Tags

NGSS.MS-PS1-5

A company is designing a fuel that will burn efficiently while following the Law of Conservation of Mass. What must their design ensure?

• The mass of fuel burned must be greater than the mass of the exhaust gases.

• The atoms in the fuel must be completely destroyed in combustion.

• The total mass of reactants and products must be equal.

• The reaction must produce more mass than it started with.

Tags

NGSS.MS-PS1-5