Illegally. Therefore, don't.
It is possible
11 years old....
No.
If she has had her period before, then yes
11 years old girl, she is a singer, actor, writer and dancer.
No.
It is a bit borderline but not entirely impossible.
Yes, it is possible (depending on how developed the girl is, of course), for an 11-year-old boy to get a 13-year-old girl pregnant.
Probably not.
NO
Don't. If you are 7 years old you are too young