- Iron is always magnetic
- Glass is always nonmagnetic
- Aluminum is always nonmagnetic
- Plastic is always nonmagnetic
- Therefore, a mixture of iron, plastic, glass, and aluminum is a mixture of magnetic and nonmagnetic material

- A mixture of iron, plastic, glass, and aluminum is a mixture of magnetic and nonmagnetic material
- Magnet can be used for separating a magnetic material from a mixture of a magnetic and nonmagnetic material
- Therefore, a magnet can separate iron from plastic, glass, and aluminum

So, a magnet can separate iron from plastic, glass, and aluminum
Question: A salvage yard contains a mixture of iron, glass, aluminum, and plastic. Which property of iron does the salvage yard take advantage of when separating the iron from the rest of the materials?
Context: - Iron is always magnetic 
- Glass is always nonmagnetic 
- Aluminum is always nonmagnetic 
- Plastic is always nonmagnetic 
- Magnet can be used for separating a magnetic material from a mixture of a magnetic and nonmagnetic material