According to the question the existing number of protons in the nucleus of a sulfur atom is 16.
According o the study of physics the common particles of an atom are known as proton, neutron and electron. It discloses that proton and neutron are located at the core of the atom. However, the exceptional study discloses that the atomic structure of hydrogen does not contain any neutron. Electron is the particle that zooms around the centre of the atom.
Moving back to the question, it can be assumed that the total number of protons in a sulfur atom = Z.
The definition of atomic mass stated that it is the sum of the quantity of protons and neutrons existing in the nucleus of an atom.
In the case of a neutral atom the number of protons and electrons are equal.
A = number of proton +number of neutrons
Again moving the question the mentioned number of electrons in the sulfur atom is 16
In a neutral atom
Number of electrons = number of protons = 16
Hence, it is proven that the present number of protons in the sulfur atom is 16.