Answer:
To determine the formal charge on the N atom in the CN- ion, we need to consider the Lewis structure of the ion.
The Lewis structure for CN- is as follows:
C ≡ N^-
In this structure, the nitrogen (N) atom has five valence electrons, four of which are involved in the triple bond with carbon (C), and one is a lone pair. The carbon atom has four valence electrons, all of which are involved in the triple bond with nitrogen.
To calculate the formal charge on the N atom, we use the formula:
Formal charge = Valence electrons of N - (Number of lone pair electrons + 0.5 × Number of bonding electrons)
For nitrogen in CN-, the formal charge would be:
Formal charge = 5 - (2 + 3 × 2) = 5 - (2 + 6) = 5 - 8 = -3
Therefore, the formal charge on the N atom in CN- is -3. The correct answer is not among the options provided.