Using preposition before whom/ which

USING PREPOSITION BEFORE WHOM/ WHICH
1. Mary has three brothers. All of them are married.
2. Tom tried on three jackets. None of them fitted him.
3. The man is my form teacher. My mother is talking to him.
4. Fortunately we had a map. We would have lost without it.
5. The woman is Jane. I can't live without her.
6. He introduced me to his students. Most of them are from Europe.
7. My uncle owns nearly 2 hundred pictures. Five of them were painted by Picasso.
8. They invited a hundred  guests. I didn't know any of them.
--> They invited a hundred  guests, ..................