Iron is a magnetic metal, and it is essential to the Earth's magnetic field!
Essentially it "records" (stores the information, maintains) the direction and orientation of the magnetic field.
Among others, the magnetic field protects the Earth from dangerous cosmic rays.
Explanation:
It is given that,
Uncertainty in the speed of an electron, 
According to Heisenberg uncertainty principle,

is the uncertainty in the position of an electron
Since, 



So, the uncertainty in its position is
. Hence, this is the required solution.
(aq)
This means it’s aqueous (dissolved in water)