Questions related graph theory | Mathematics homework help

I need to get answers for some questions related to Graph Theory. I

** The Questions:  (inside the attached file)

[1] 6.1.28 
[2] 6.3.3 
[3] 6.3.19 (When proving graph is not hamiltonian, you should use proof by contradiction) 
[4] 6.5.11 (prove why you can’t find a hamiltonian circle ) 
[5] 6.5.12 (prove why you can’t find a hamiltonian circle )