A ball slowing down as it rolls across a carpet is an example of friction.
Friction is a force that slows down moving objects.
High iron and magnesium rocks have a high percentage of dark-colored (mafic) minerals.
So the high iron and magnesium would be darker than the low iron and magnesium.
Answer: 
Explanation:
According to the law of conservation of mass, mass can neither be created nor be destroyed. Thus the mass of products has to be equal to the mass of reactants. The number of atoms of each element has to be same on reactant and product side. Thus chemical equations are balanced.
The balanced equation will be:

In ionic bonding, an arrow is often drawn on the diagram to show the direction the electrons move to form the ions.