What are the structural differences between the nine possible isomers of heptane(c7h16)?

Heptane has nine structural isomers are 2-methylhexane, 3-methylhexane, 2,2-dimethylpentane, 2,3-dimethylpentane, 2,4-dimethylpentane, 3,3-dimethylpentane, 3-ethylpentane and 2,2,3-trimethylbutane. Each compound must have the same molecular formula  but the structure of each are different from each other.

Zinc contains about 30 protons 

Descriptive investigations are mainly questions to uncover information. it does not have an hypothesis. it's mainly gathering information, it is not repeatable as you are just asking questions.