During a science lesson on changes, Ms. Sloan's students made mixtures of sulfur (the yellow substance) and iron filings (the black substance. Ms. Sloan challenged her students to separate the two substances and one group easily completed the task by using a magnet to lift the iron filings from the mixture.
Next, Ms. Sloan poured the same mixture into a test tube and heated it in the Bunsen burner flame.

What was the result of heating the mixture? All BUT ONE choice is correct.
A) A chemical change took place.
B) A chemical compound, iron sulfide, was formed.
C) Both substances melted and became a solution.
D) The iron filings could not be separated with a magnet.

19. explain why a magnet from your refrigerator could not be used to lift something as heavy as a car. (chapter 7 – pages 202-203) 20. can a magnet ever have a single pole? explain your answer. (chapter 7 – page 208) 21. what happens to the wavelength of a wave if the frequency is increased? (chapter 9 – pages 280-281) 22. an ocean wave has a wavelength of 10 m and a frequency of 4.0 hz. what is the velocity of the wave? show the appropriate equation from your book and show your work with units. (chapter 9 – page 282) 23. as you sit outside, the sound of a siren becomes lower in pitch. is the emergency vehicle moving away from or towards you? explain how you know. (chapter 10 – page 315-316) 24. why are two astronauts in space unable to hear one another? (chapter 10 – page 307) 25. explain in at least 3 sentences how electromagnetic waves form. (chapter 11 – page 338-339) 26. using the chart on page 345 in your textbook, what are the three types of electromagnetic wave with wavelengths shorter than those of visible light. give an example of each. (chapter 11 – pages 345-351) 27. explain why a leaf usually appears to be green, but a rose typically appears red. (chapter 12 – page 373) 28. what is the difference in light that is refracted compared to light that is reflected? think in terms of speed of light as well as what happens to light waves when they interact with a medium. (chapter 12 – pages 369-370) 29. how are concave and convex lenses different? (chapter 13 – page 408-410) 30. what type of mirror is used in rearview mirrors in cars? why is it important that these mirrors have the warning, “objects in mirror are closer than they appear.”? (chapter 13 – page 405)

The free body diagram shows a box being pulled to the left up a 25-degree incline. the magnitude of the normal force is

The cerebellum controls? thirst sensations sleep-wake cycles hand-eye coordination heart rate and pulse