Here's how to determine the number of sulfur atoms in the reaction:

1. Balance the chemical equation:

The balanced chemical equation is:

2 H₂S + SO₂ → 3 H₂ + 2 S

2. Count the sulfur atoms:

* On the reactants side (left side), there are 3 sulfur atoms (2 from H₂S and 1 from SO₂).

* On the products side (right side), there are 2 sulfur atoms (from the 2 S).

Therefore, there are a total of 3 sulfur atoms on the reactants side and 2 sulfur atoms on the products side in the balanced chemical equation.