Question

below is a resonance structure for no3-. label the formal charges on the selected atoms.

Explanation:

Step1: Recall formal - charge formula

The formula for formal charge is $FC = V - N - \frac{B}{2}$, where $V$ is the number of valence electrons, $N$ is the number of non - bonding electrons, and $B$ is the number of bonding electrons.

Step2: Calculate formal charge of nitrogen

Nitrogen ($N$) has 5 valence electrons ($V = 5$). In the $NO_3^-$ structure, it has 0 non - bonding electrons ($N = 0$) and 8 bonding electrons ($B = 8$). Using the formula $FC=V - N-\frac{B}{2}$, we get $FC = 5-0 - \frac{8}{2}=5 - 4=+ 1$.

Step3: Calculate formal charge of single - bonded oxygen

Oxygen ($O$) has 6 valence electrons ($V = 6$). A single - bonded oxygen in $NO_3^-$ has 6 non - bonding electrons ($N = 6$) and 2 bonding electrons ($B = 2$). Using the formula $FC = V - N-\frac{B}{2}$, we get $FC=6 - 6-\frac{2}{2}=6 - 6 - 1=-1$.

Step4: Calculate formal charge of double - bonded oxygen

Oxygen ($O$) has 6 valence electrons ($V = 6$). A double - bonded oxygen in $NO_3^-$ has 4 non - bonding electrons ($N = 4$) and 4 bonding electrons ($B = 4$). Using the formula $FC = V - N-\frac{B}{2}$, we get $FC=6 - 4-\frac{4}{2}=6 - 4 - 2=0$.

Answer:

Nitrogen has a formal charge of +1. Single - bonded oxygen has a formal charge of - 1. Double - bonded oxygen has a formal charge of 0. So for the multiple - choice options, if we assume we are asked about nitrogen, the answer is D. +1.