if it is known that AB is a candidate key of R(A,B,C,D) which subsets of ABCD cannot be a candidate key? Please justify your answer

Given a relation schema R with n attributes R(A1, A2, ..., An). Whats the maximum number of possible super-keys for R? Please justify your answer.

Given a relation schema R with n attributes R(A1, A2, ..., An). Whats the maximum number of possible candidate keys for R? Please justify your answer.