Answer: The correct option is A.
Explanation: The given molecules are the molecules of same element.
These molecules are considered as diatomic species.
Polar molecules are the molecules in which some polarity is present in the bond. These molecules are formed when there is some difference in the electronegativities of the elements. Example: HCl
Non-polar molecules are the molecules where no polarity is present in the bond. These molecules are formed when there is no difference in the electronegativities of the elements. Example: 
The given molecules are non-polar in nature.
Hence, these molecules must be non-polar. So, the correct option is A.
Answer:
Explanation:
By rearrangement of atoms of reactants. The entire properties will also different from the reactants as the composition changes.
Because Na has one too many electron to be stable, while Mg has 2. once they loose those electrons, they will be come ion. loosing one electron will give the ion a 1+ charge, and loosing 2 will create a 2+ charge