Which type of reaction has the general formula of AB + CD → AD + CB?

synthesis
decomposition
oxidation
replacement

It would be replacement

Because electrons have negligible mass, to account for the mass of the isotope, there must be 16 neutrons, 16 neutrally charged, massive, fundamental particles present in the sulfur nucleus. and thus finally, if we have the 32s2− ion, there are 18 electrons, 16 protons, and 16 neutrons.

True, the standard unit for volume is liters which can be represented by either a lower case "l" or a capital "l"