Draw the lewis structure(s) for the molecule with the chemical formula c2h3n, c2h3n, where the n is connected to only one other atom. how many double bonds are there in the correct lewis structure?

The possible structure for given Chemical formula is given below, It is asked that the Nitrogen atom is connected to only one atom. As, nitrogen is involved in making three bonds so it is only possible for Nitrogen to make three bonds with Carbon atom having the capacity of forming four bonds. The possible structure is Acetonitrile. In which N is connected to Carbon atom through triple bond as shown below,

Result:
          In current structure in which N is attached to only one atom, there is no double bond. So, the answer is ZERO.

They are all decomposition reactions.