Choose A, B, C, or D for the correct answer.

The following text is for questions 30 to 33.

Purpose:

To determine the basic difference between homogeneous and heterogeneous mixtures

Materials:

• empty 20-ounce (600 ml) water bottles with caps
• tap water
• 1/2 teaspoon (2.5 ml) table salt
• masking tape
• a pen
• a timer
• 3/4 cup (63 ml) liquid cooking oil

Steps:

1. Fill one of the bottles to approximately three-quarters full with water.
2. Add the salt to the bottle of water and secure the cap.
3. Use the tape and pen to label the bottle "Homogeneous Mixture".
4. Shake the bottle vigorously 20 or more times. Allow the bottle to stand for 2 to 3 minutes.
5. Fill the second bottle to approximately half full with water.
6. Add the cooking oil to the bottle and secure the cap.
7. Use the tape and pen to label the bottle "Heterogeneous Mixture."
8. Shake the bottle vigorously 20 or more times. Allow the bottle to stand for 2 to 3 minutes.
9. Compare the contents of the bottle.

Result:

The homogeneous mixture looks the same throughout, but the heterogeneous mixture has two separate layers.

Adopted from: janice VanCleave, Teaching the Fun of Science, Canada, john Wiley & Sons, Inc., 2001.

What do we use the pen for?