Which of the following has the greatest mass, in grams?

a. 1 atom of gold (Au)

b. 1.0 mol mercury (Hg) atoms

c. 2.0 mole of chlorine (Cl) atoms

d. 25 atoms of mercury (Hg)

Mole represents the a huge Avogadro number (way larger than atom), so we can eliminate option A and D.

And we know that Mercury is a solid, which mean it has greater mass than chlorine

So the answer is : B. 1.0 mol mercury (Hg) Atom