To determine the number of atoms in 5.10 moles of sulfur, we just have to multiply the given number of moles by the Avogadro's number. That is,
(5.10 moles) x (6.022 x 10^23 atoms / mole)
= 3.07 x 10^24 atoms
Thus, there are approximately equal to 3.07 x 10^24 atoms of sulfur gas.