Final answer:
The structure in question contains 12 hydrogen atoms, confirming that option (a) is the correct answer. The student asked how many total hydrogen (H atoms) are present in the structure described. The structure is a six carbon molecule with a double bond on the third and fourth carbon from the left.
Step-by-step explanation:
The student asked how many total hydrogen (H atoms) are present in the structure described. The structure is a six carbon molecule with a double bond on the third and fourth carbon from the left. According to the information provided, there are twelve hydrogen atoms in total (12 H atoms), which is supported by the statement that each side of an equation consisting of this molecule has 12 hydrogen atoms. Therefore, the correct answer is 12 hydrogen atoms, corresponding to option (a).