Chemical Changes Assessment Questions Gizmos Verified And Accurate Answers.

A white powder is added to a solution. The images show observations made before the powder is added, just after the powder has been added, and a little while later. (The liquid in the small beaker is phenol red solution.) What evidence shows that a chemical change has taken place? - correct answer Correct Answer: D. All of the above. A reaction produces a gas, which is collected in a glass cylinder. When a glowing splint is placed inside the container, it burns brightly, as shown. Which gas was produced in the reaction? - correct answer Correct Answer: B. Oxygen A chemical reaction is done in the setup shown, resulting in a change of mass. What will happen if the same reaction is done in a sealed container that is placed on the electronic balance? - correct answer Correct Answer: B. The mass will stay the same because the gases produced in the reaction are kept inside the container. Based on its formula, what type of chemical reaction occurs between silver nitrate (AgNO3) and copper (Cu)? 2AgNO3 + Cu → 2Ag + Cu(NO3)2 - correct answer Correct Answer: C. Single replacement When hydrogen peroxide (H2O2) is added to potassium iodide (KI) solution, the hydrogen peroxide decomposes into water (H2O) and oxygen (O2). The chemical equation for this decomposition reaction is: 2H2O2 → 2H2O + O2 - correct answer Correct Answer: D. Catalyst