Which transition metals are paramagnetic but can easily form ferromagnetic alloys with other metals? A. Transition metals in groups 1-5, periods 5 and 6
B. Transition metals in groups 8-10, periods 5 and 6
C. Transition metals in groups 8-10, periods 4 and 5
D. Transition metals in groups 11 and 12, periods 4 and 5

Los metales de transición son aquellos elementos químicos que están situados en la parte central del sistema periódico, en el bloque D, cuya principal característica es la inclusión en su configuración electrónica del orbital D, parcialmente lleno de electrones. Esta definición se puede ampliar considerando como elementos de transición a aquellos que poseen electrones alojados en el orbital d, esto incluiría a zinc, cadmio, y mercurio. La IUPAC define un metal de transición como "un elemento cuyo átomo tiene una subcapa d ( subnivel de energía) incompleta o que puede dar lugar a cationes".1

answer : a model is often used to explain and make things easier to understand when any scientific topic needs to be demonstrated and explained.

as in this case where a scientist wants to use a model to present the results of his detailed scientific investigation. he should do it as it will him to make the audience understand the concept in a much better way. also, it can be changed according to new scientific understandings.