Concept:Materials that are strongly attracted to a magnet are called ferromagnetic materials. Iron, nickel, and cobalt are examples of such materials.
Explanation:Option A: Correct. Heating a magnet gives energy to its magnetic domains. Their alignment gets disturbed. So the magnet loses its properties.
Option B: Correct. When bar magnets are kept with unlike poles together, they help maintain each other's magnetic strength. The field lines remain closed, reducing loss of magnetism.
Option C: Correct. Like poles (North–North or South–South) repel each other. This is a basic property of magnets.
Option D: Incorrect. Nickel and cobalt are ferromagnetic metals. They are strongly attracted to a magnet. So this statement is false.
Answer:Option D is the incorrect statement.