The problems collected in this chapter deal with Particle Physics from a phenomenological viewpoint. Whenever possible, the problems ask for numerical calculations, even though these are more properly estimates than actual calculations. This is because at introductory level the mathematical techniques are not yet available. In the first section, the general properties of the fundamental interactions are addressed. For this purpose, tools like Feynman diagrams and conservation properties are used. The further two sections are more specific in electro-weak and strong interactions.