What is the minimum length required for white hairs to constitute a sign of tzara'at impurity?
Halacha 1 states that white hairs must be long enough to be pulled out by tweezers (a zug). A hair that is shorter does not qualify as a sign of impurity.
Question 2
Two white hairs are found inside a baheret, but they are rooted within a boil that is inside the baheret. What is the ruling?
Halacha 4 states that white hair is only a sign of impurity when it is in the baheret itself. Hair growing inside a boil, burn, or bohak within the blemish does not qualify, and the person is isolated.
Question 3
A person had white hair that predated the appearance of the baheret. What is the ruling?
Halacha 6 states that white hair is a sign of impurity only when the baheret preceded and turned it white (from Leviticus 13:10). If the hair existed before the baheret, the person is treated as if there were no sign and isolated.
Question 4
What is 'entrusted hair' (se'ar pekudah)?
Halacha 7 explains: when a first baheret caused white hair, then disappeared (leaving the hair), then a second baheret returned to the same location — that white hair is called 'entrusted hair' and is NOT a sign of impurity, since a different baheret turned it.
Question 5
Two white hairs are found scattered within a gris-sized baheret, with black hair between them. What is the ruling?
Halacha 2 explicitly states that two white hairs in a blemish — even with black hair between them — constitute a sign of impurity. The space of black hair does not reduce the gris measurement.