Topics covered:

Chapter 2, Mishna 2

If prohibited chametz (either because during Passover or because after Passover by the chametz was owned by a Jew during Passover) becomes mixed with a permitted food, is the mixture prohibited? Depends on 1) did the mixing happen during or after Passover, 2) what is the proportion of prohibited chametz to permitted food in the mixture and 3) whether you’re asking Rav, Shmuel or Rabbi Yochanan.