You should read up on Proust's law, better known as the Law of Definite Proportions. This is a chemical law that defines your question more generally, on why the ratio of elements and ions are always fixed.
Basically, this compound Magnesium(II) Chloride is MgCl2 because it has the same number of protons, neutrons, and electrons all the way. This defines the properties of the compound or atom.
Supercritical mass results to an increase in the rate of fission. There is a chain reaction that will occur. Nuclear fission or explosion used in atomic bombs relies on supercritical mass. An atom splits into two, with each splitting into two pairs and so on, releasing energy in each step.
A because magma is underground
Answer:
10/3 m/s. v=d/t. so 100/30 = 10/3