Chemistry Quiz 7/8

Omar and Yahya are observing ice melting into water. What is this process an example of?

• A change in state or form with no new substance forming

• A chemical reaction involving new substances

• A change in temperature only

• A change in color only

During a science experiment, Mohammed and Murad observed a chemical reaction in a closed container. What principle explains why the mass of the container and its contents remained the same before and after the reaction?

• Mass is lost during a chemical reaction

• Mass is created during a chemical reaction

• Mass remains constant during a chemical or physical change

• Mass is only conserved in physical changes

Hala and Rayan are making lemonade. What is an example of a physical change?

• Burning wood

• Dissolving sugar in water

• Rusting iron

• Baking a cake

During a science experiment, Mohammed and Yahya mixed two clear solutions together. What can indicate that a chemical reaction has occurred?

• Change in temperature

• Change in color

• Emission of light

• All of the above

What is an exothermic reaction?

• A reaction that absorbs heat from its environment

• A reaction that releases heat to its environment

• A reaction that produces light without heat

• A reaction that changes color

Moaz and Yasmin are conducting an experiment to observe the formation of rust on iron nails. What is the balanced chemical equation for the formation of rust?

• 4Fe + 3O₂ + 6H₂O → 4Fe(OH)₃

• 2Fe + O₂ + 2H₂O → 2Fe(OH)₂

• Fe + O₂ + H₂O → FeO(OH)

• 3Fe + 2O₂ + 3H₂O → 3Fe(OH)₂

During a science experiment, Mohammed and Omar observed a reaction in a dark room where a glow was produced without any noticeable heat. What is this phenomenon called?

• Light emission from a living organism

• Light emission from a chemical reaction without heat

• Light emission from a hot object

• Light emission from a color change

What is an example of a chemical reaction that produces a gas?

• Mixing baking soda and lemon juice

• Burning wood

• Rusting of iron

• Melting ice

What does a chemical equation represent?

• A mathematical calculation

• A chemical reaction

• A physical change

• A biological process

In a chemical equation, what is the role of the arrow?

• It shows equality

• It indicates a physical change

• It shows the conversion of reactants to products

• It represents a mathematical operation