Which resonance contributor of acetic acid actually exists?

Which of the following correctly represents a valid resonance structure for the cyanate ion $C_N{-}^1$ ($\mathrm{CNO}-$)?

For each pair of ions, determine which ion is more stable. Use resonance forms to explain your answers.

(e)

(f)

In the following sets of resonance forms, label the major and minor contributors and state which structures would be of equal energy. Add any missing important resonance forms.

(d)

(e)

Use resonance structures to identify the areas of high and low electron density in the following compounds:

(a)

(b)

(c)

Draw the important resonance forms to show the delocalization of charges in the following ions. In each case, indicate the major resonance form(s).

(j)

(k)