Answer:
<h3><em><u>Magnesium has an atomic number of 12, which means its neutral atom has 12 electrons. The Mg2+ ion is formed when the neutral magnesium atom loses 2 electrons, which brings its total number of electrons to 10</u></em></h3>
It loses it's fuel supply from the water and begins to weaken
image distance,di=10 cm
object distance,do=20cm
magnification, m=di/do
=10/20
=0.5
since the image is virtual, magnification is negative.
therefore m=-0.5
