The law of conservation of energy applies:
a. whenever pe = 0.
b. in isolated systems.
c. in all systems
d. only in open mechanical systems.

this means that the temperature of both substances will be equal

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.

helium

oxygen

neon

sodium