Solution to 5.

 

{(p<->q)&~p}<->~p

 p  q  ~p  p<->q  (p<->q)&~p  {(p<->q)&~p}<->~p
 T  T  F  T  F  T
 T  F  F  F  F  T
 F  T  T  F  F  F
 F  F  T  T  T  T

 

The statement is a contingency, as can be seen by the fact that there are both Ts and Fs in its truth column.