Chemical, potential energy is stored in a battery.
The negative end of a battery is connected to a wire.
The wire loops numerous times around an iron nail.
The wire is connected to the positive end of the battery.

What would happen to a piece of iron if it were placed close to this device?
A) It begins to spin.
B) It gains a negative charge.
C) It gains a positive charge.
D) It moves toward a piece of iron.

Explanation:

The description of the built device corresponds to a temporal electromagnet: as long as the battery is connected and supplying the potential difference (voltage) the iron nail will have magnet properties.

Since magnets attract and are attracted to iron, the iron nail and the piece of iron would feel attracted to each other.

The question is confusing because it asks what would happen to a piece of iron if it were placed close to this device, but it should be what happens to the iron nail if a piece of iron were placed close to this device.

Then, assuming the iron nail is free to move it would move toward the piece of iron due to the electromagnetic force.

considering the question as per the attachment

here we can see that the radon nuclide has 222 as the atomic mass number and 86 as the atomic number.

when it undergoes nuclear fission it gives polonium which has atomic mass number as 218 and atomic number will be 84 along with a helium nucleus which has 4 atomic mass number and 2 as its atomic number.

222 = 218 + 4 (atomic mass number)

86 = ? + 2; therefore ? = 86-2 = 84.

the atomic mass number of polonium will be 84.