The chemical formula for magnesium chloride is Cl₂Mg.
It’s b I just looked it up

Actually Welcome to the Concept of the Ionic bonds.
Since Sodium (Na) is a cation and Chlorine (Cl) is a Anion, they both form a Ionic bond called as NaCl (common salt)
So answer is, Na and Cl
Answer - A substance is matter that has a uniform and definite composition. All samples of substances, sometimes called pure substances, have identical properties.
Answer:
Since different isotopes of an element have different numbers of neutrons (but always the same number of protons) they have different mass numbers. Nitrogen-14 and nitrogen-15 are both stable isotopes of nitrogen. However, the other 5 isotopes are all unstable.