Respuesta :
Solving for the percent composition by mass of sulfur. The formula would be:
%S = mass of sulfur / mass of compound x 100%
Plugging in our data:
%S = 32 amu / 120 amu x 100%
%S = 0.266666 x 100%
%S = 26.66%
Rounded off to two significant numbers it will be 27%. Therefore the answer is number 2.