Explanation:
We can start with the last one and we have to find the longest chain possible. I think there are two possibilities and they have the same number of C atoms.
The length of the longest carbon chain is 7 atoms of C.
If the bottom chain of C atoms is bonded to the carbon on the right all the possible chains have the same result.
The length of the longest carbon chain is 9 atoms of C.
If the bottom chain of C atoms is bonded to the carbon on the left all the possible chains have the same result.
The length of the longest carbon chain is 8 atoms of C.
In this case each vertex represents an atom of carbon (if it is not written like the one in the left).
The length of the longest carbon chain is 7 atoms of C.
Answer:
1st ---> 7
2nd ---> 8 or 9
3rd ---> 7
