Draw Lewis structures for the fulminate ion including possible resonance forms. Draw the molecule by placing atoms on the grid and connecting them with bonds. Include all hydrogen atoms and nonbonding electrons. Use square brackets to denote the overall charge.

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Explanation:

The fulminate ion, CNO − , is a pseudohalic ion because its charge and reactivity are similar to those of the halogens. Due to the instability of the ion, fulminate salts are friction-sensitive explosives. The best known is mercury(II) fulminate, which has been used as a primary explosive in detonators(Wikipedia).

The most important contributing structure is the one in which the formal charges on carbon, nitrogen and oxygen are; -1, +1, -1 as shown in the image attached to this answer.

answer; 4 electrons;