Solution
     Do not be too greedy !

Problem 1. You can not capture all.  Do not care the snapback (F7,F6,G4,E8,F4) .

Problem 2.  (F2,J2,H2,H3,H3,J4,G2,K2,H1,L2).  Then N7 or E2.

Problem 3. Do not try the snapback(O1) .

Problem 4. You can connect the black stones in sente.  (L2 ,H6,N1,K8กห

Problem 5.  No hint