Week 3 Pre-Quiz

A student places a piece of a potato into a container of hydrogen peroxide. One observation the student makes is that bubbles form around the potato. The presence of bubbles might indicate the formation of a new substance because bubbles - 

• could show that a gas is forming
• always rise to the top of a liquid. 
• are almost always perfectly spherical.
• usually burst after a few minutes.

Four students performed four different investigations by combining different substances. Their results are shown in the table provided. In which experiment are new substances being formed?

• Experiment 1
• Experiment 2
• Experiment 3
• Experiment 4

Hydrogen peroxide breaks down to form water and oxygen gas. Which observation is evidence that a chemical reaction has occurred?

• The mass of the solution remains the same.
•  Phase changes are observed.
•  The color of the solution remains clear.
• The temperature of the solution increases. 

A clear liquid from a flask is poured into another clear liquid in a beaker. Which of the following results of this procedure would indicate a new substance was formed?

• The level of the substance in the beaker is higher after the other liquid is added.
• A yellow solid forms and then settles to the bottom of the beaker.
• Small white crystals are left behind in the flask that held the first liquid.

A copper penny turning greenish after a few years is an example of ...

• Chemical Change
• Physical Change

A change in which NEW substances are formed.

• Chemical change
• Physical change
• Casual change
• Formal change

Which of the following is NOT an example of chemical change?

• sour milk
• burning wood
• breaking a pencil
• rust

Ripping up paper ...

• Chemical Change
• Physical Change

A change in phase ...

• Chemical Change
• Physical Change

Evidence of a physical change.

• New substance
• Shape Change
• Light produced
• Gas released.