To solve the problem, we need to identify the non-metal element from the given options.
1. Identification of Metals and Non-metals:
- Pb (Lead) is a metal.
- Sn (Tin) is a metal.
- K (Potassium) is a metal.
- S (Sulfur) is a non-metal.
Final Answer:
The non-metal among the following is $ {S} $ (Sulfur).