a) Cobaltb) Copperc) Irond) Nickel
The four most-common and alloys and metals are Iron, Nickel, Steel, Cobalt. Say this to yourself a few times to get it in your head and you'll have no more problems with magnetism. Therefore a, c and d are the answers
Well, I know you can't pick copper up with a magnet. Iron would be my guess.
The three metals [not alloys] that are strongly magnetic are iron, nickel and cobalt. Steel is magnetic, though it is an alloy and not purely metal. Magnetic domains exist within a material, and they have a north-seeking pole and a south-seeking pole. When a particular materials is not in the presence of a magnetic field, these domains are misaligned and are positioned randomly. For that reason, the magnetic field produced by each domain gets cancelled by another domain in the opposite direction. Most of the force from the material as a whole is cancelled, so the material hardly exhibits any magnetism. A magnetic material is a material where the domains can be easily aligned. Examples of these materials are stated above. When a magnetic material is brought into a magnetic field, the domains present within the material will align to match the magnetic field surrounding it. This ensures almost no cancellation of the field from misaligned domains- the force is carried effectively. If a non-magnetic material is brought into a magnetic field, its domains hardly or don't get aligned, so the force cannot be carried effectively. It gets cancelled throughout much of the material, and thus the material does not exhibit magnetic properties. There is evidence enough that atoms themselves are magnets, and the theory is that aligned atoms and domains produce a magnet. Aligned domains with atoms whose spins do not align may produce magnetic materials. To answer your question, the answer is (a), (c) and (d). Hope I helped. Cheers(:
