Here's how to calculate the percent composition of sulfur in SO2:

1. Find the molar mass of SO2:

* Sulfur (S): 32.07 g/mol

* Oxygen (O): 16.00 g/mol (x 2 since there are two oxygen atoms)

* Total molar mass of SO2: 32.07 + (16.00 x 2) = 64.07 g/mol

2. Calculate the mass percentage of sulfur:

* (Mass of sulfur / Molar mass of SO2) x 100%

* (32.07 g/mol / 64.07 g/mol) x 100% = 50.04%

Therefore, the percent composition of sulfur in SO2 is approximately 50.04%.