[poll id=”77″]
ANSWER: D. -1/3
The entire compound has a charge of 0. Thus, giving Na’s +1 oxidation state: 1 + 3x = 0
The 3x represents the nitrogen (3 of them, x being the unknown oxidation number), the 1 represents the +1 oxidation number of Na and finally the 0 being the neutral charge of the entire compound. Solving for x:
3x=-1
x=-1/3