How many experimental trials are needed before a hypothesis can be accepted as true ?

Approximately, or at least the test must be repeated until 3 times, to find an accurate average and hypothesis.

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.

100%sorry if i’m wronghope this good luck: )