Final answer:
The structural formula given represents a six carbon molecule with a double bond on specific carbon atoms. The question asks how many hydrogen atoms are needed to complete the structure.
Step-by-step explanation:
The structural formula given, C=C-N-C, represents a six carbon molecule with a double bond on the third and fourth carbon from the left. In this structure, there are twelve hydrogen atoms in total. Each carbon atom typically forms four single bonds, and each nitrogen atom forms three single bonds. The remaining electrons on the carbon atoms should be paired with hydrogen atoms to complete the structure.
Therefore, the correct answer is a. 6. You would need six hydrogen atoms to complete the given structure.