Chemical Reaction

What is a chemical reaction?

• A process that changes the physical state of a substance

• A process where one or more substances are converted into new substances

• A method of separating mixtures

• A process that only changes the shape of an object

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

• Change in color

• Formation of a precipitate

• Change in size

• Production of gas (bubbles)

What type of reaction occurs when two or more reactants combine to form a single product?

• Decomposition

• Combination (Synthesis)

• Single Replacement

• Double Replacement

Which of the following is an example of a decomposition reaction?

• H₂ + O₂ → H₂O

• NaCl + AgNO₃ → NaNO₃ + AgCl

• 2H₂O₂ → 2H₂O + O₂

• Zn + HCl → ZnCl₂ + H₂

What happens in a single replacement reaction?

• A single compound breaks down into two or more simpler substances

• Two elements or compounds combine to form a more complex compound

• An element replaces another element in a compound

• Two compounds exchange ions to form new compounds

Which of these is an example of a combustion reaction?

• HCl + NaOH → NaCl + H₂O

• CH₄ + 2O₂ → CO₂ + 2H₂O

• Fe + CuSO₄ → FeSO₄ + Cu

• CaCO₃ → CaO + CO₂

What law explains why the mass of reactants must equal the mass of products in a chemical reaction?

• Law of Conservation of Energy

• Law of Conservation of Mass

• Law of Universal Gravitation

• Law of Motion

When iron reacts with oxygen to form rust (Fe₂O₃), what type of reaction is this?

• Combustion

• Combination

• Decomposition

• Single Replacement

Which of the following equations is correctly balanced?

• H₂ + O₂ → H₂O

• 2H₂ + O₂ → 2H₂O

• H₂ + O₂ → 2H₂O

• 2H₂ + 2O₂ → H₂O

What type of reaction occurs when two compounds exchange ions to form new compounds?

• Combination

• Decomposition

• Single Replacement

• Double Replacement