Answer
a) O = +1; B= -1.
b) C+-1, N = +1,0.
c) N(middle) =+1, N = -1
d) O (outer layer)= 0, O(middle layer) =+1, O (right layer)=-1
e) C= -1, P= +1
f) N=+1, O= -1
Work Step by Step
Make notice that V is the number of valence electrons of the neutral atom in isolation during its ground state. N is the number of non-bonding valence electrons on this atom. And lastly, B is the total number of electrons shared in bonds with other atoms in this molecule.