When do P waves arrive at the surface in relation to S waves and surface waves? ( Must be in your own words)

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"