Disjunctive Normal Form Problem

For each of the following propositional wff’s over the variables P, Q and R indicate if it is not in DNF, in DNF, or in full-DNF

Please explain why

(a) (P ∧ Q) ∨ (P ∧ ¬Q)
(b) P ∧ R ∧ Q
(c) ¬(P ∧ R)
(d) P
(e) P ∨ R
(f) P ∧ (Q ∨ R)