Steel.
The magnetic material of which the box of the refrigerator is fabricated, such as iron or steel.
Cotton and Steel mills
Usually steel with some coating over that (e.g. paint, plastic).
Plastic offers a number of important advantages as a construction material. It is relatively inexpensive and weighs very little, as compared to using something like marble, glass, stainless steel, or granite for the walls of your refrigerator. It is waterproof, giving it an advantage over wood or particle board or cotton. Also it is a poor conductor of heat.
If you mean the air around them is 0 degrees, then the steel would be colder.
An example of a raw material is cotton, which can be processed into thread, which can then be woven into cloth, a semi-finished material. Cutting and sewing the fabric turns it into a garment, which is a finished material. Steelmaking is another example-raw materials are mined, refined and processed into steel, a semi-finished material. Steel is then used as an input in many other industries to make finished products.
Generally it's stainless steel. I've never heard of a leather fridge in my life.
cotton
the refrigerator is iron or steel, therefore the magnet sticks to it.
Because it is made up of iron and steel!
Steel, plastic and insulating foam.
Steel, and plastic are the main components.