How many gold atoms are contained in 0.650 grams of gold?

Moles of gold = mass of gold/atomic weight of gold
                       =   0.65/196.967 
                       =    3.3 x 10^-3 

Number of gold atoms = moles x 6.02 x 10^23 
                                    = 1.98 x 10^21 atoms

Hope this helps!

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.