Answer: Iron.
- A Aluminium
- B Iron
- C Copper
- D Bismuth
Correct answer: B. Iron
Explanation: Iron (along with cobalt and nickel) is ferromagnetic, showing strong attraction to an external field and retaining magnetism once the field is removed.
Magnetic field of a bar magnet: field lines emerge from the north pole and re-enter at the south pole outside the magnet, forming continuous closed loops. Image: Geek3, CC BY-SA 3.0, via Wikimedia Commons.
Concept context
Bar magnets, Earth's magnetism, and how different materials respond to an external magnetic field - diamagnetic, paramagnetic, and ferromagnetic behaviour.