8th Grade Quiz (Chemical Reaction)

1. 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?

• A gas is produced

• The pH changes

• The temperature changes

• All of the above

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-4

NGSS.MS-PS1-5

2. 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?

• Hydrogen

• Oxygen

• Carbon dioxide

• Ammonia

Tags

NGSS.MS-PS1-2

3. 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?

• The mass will decrease because matter is lost in this reaction.

• The mass will stay the same because the gases produced in the reaction are kept in the container.

• The mass will increase because the solid react with gas to produce more solid.

• There is not enough information to predict whether the mass will increase, decrease, or stay the same during the reaction in a closed container.

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

4. 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

In this reaction, the potassium iodide is needed for the reaction to happen, but it isn’t changed in the reaction and can be used again. What is the role of potassium iodide in this reaction?

• Reactant

• Product

• Precipitate

• Catalyst

5. Based on its formula, what type of chemical reaction occurs between silver nitrate (AgNO3) and copper (Cu)?

2AgNO₃ + Cu → 2Ag + Cu(NO₃)₂

• Synthesis

• Decomposition

• Single Replacement

• Double Replacement

6. A student observes that a gas is formed when chemical Y is added to chemical Z in the lab. The student’s observation of a new product being formed is the common outcome of all

• physical changes

• chemical changes

• mass changes

• phase changes

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

7. A chemical equation is shown in the picture. Which substance is a reactant?

• NaCl

• Cl

• H2

• NaOH

Tags

NGSS.MS-PS1-2

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8. In a chemical reaction, the _________ are always written on the right side of the equation.

• reactants

• coefficient

• products

• subscripts

9. In a(n) _____________ system, matter cannot enter or leave.

• physical

• open

• chemical

• closed

10. For a process to be defined as a chemical reaction, _____ must be produced.

• a new substance

• the same substance

• light

• more mass

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5