Answer :
Answer:
1) 157 Neutrons, 2) the decimal is simply is due to isotopes, because the elements atomic mass is an average of these isotopes multiplied by its abundance(or percentage on earth.) For Mercury, it has many isotopes(an element with a different mass number, logically the atomic mass listed on the periodic table as a mass has 100% abundance, therefore this is used to find the most abundant mass for that particular element/molar mass) likewise, Mercury has an atomic mass of 200.59 u, as one mol of Hg(mercury) is 200.59 grams.
Explanation:
The formula for Neutrons in an atom of an element is calculated by finding the