When two substance mixed together what does not indicate that a chemical reaction has

When two substances are mixed together, a color change is observed. This observation is not enough evidence that there is a chemical reaction happening because color changes are not indicators of chemical reaction:

your answer is c! hope this : )

the answer is the first electromagnet (a). this is because it has more coils around the ferromagnetic material. increasing the number of coils increases the surface area in which the metal interacts with the current in the coil. this enables more atoms in the metal to become aligned hence becoming more magnetized.