How many substances convey all three types of impurity (touch, carrying, and ohel)?
Halacha 1: The Rambam lists 12 entities that convey all three types: corpse, olive of flesh, olive of netzal, properly-fleshed limbs (from live or dead), spine, skull, majority structure, majority count, quarter-kab bones, revi'it blood, and dam tevusah.
Question 2
Under what burial conditions does rekev (decomposed matter) form validly?
Halacha 4: Rekev only forms when a corpse is buried naked in a marble or glass coffin and was completely intact — not in wood, clothing, or metal coffins, and not when buried with others.
Question 3
If one person touches a half-olive of flesh and simultaneously has another half-olive of flesh resting above them (ohel), do these combine for impurity?
Halacha 15: Touch and ohel are separate categories (shemot). They do not combine with each other. Only same-category half-measures combine — e.g., touching two half-olives simultaneously or being under ohel covering two half-olives.
Question 4
What is the status of worms that emerge from corpse flesh?
Halacha 10: Worms that emerge from corpse flesh are pure, whether alive or dead. Similarly, powdered flesh and ashes of burned corpses are pure.
Question 5
The Rambam's reasoning for why revi'it blood, quarter-kab ohel, and deficient limbs are not Scriptural impurities is based on which principle?
Halacha 3: Rambam states his view — since a nazirite does not shave for these impurities (as explained in Hilchot Nezirut), and nazirite shaving applies only to Scriptural corpse impurity, these must be Rabbinic in origin.