Which of these would have the highest boiling point? I am very confused:(

Been mulling over this for half an hour and I still can't decide, I need to write the compound with the highest and the compound with the lowest boiling point - they're all hydrocarbons, and I know that it depends on how many carbons are in the chain and how many branches it has, but by carbons in the chain does it mean 5 in pentane even if it has 2 methyl groups? or does this mean it has a 7 carbon chain?

Here's what I have
- 2,2 - Dimethylhexane
- 1,1,2,2, tetramethylbutane
- 2,3,3 - trimethylpentane
- 4 - Methylseptane (has 7 in longest full chain I guessed it would be called sept so might be wrong)

Any help would be gratefully appreciated

Thanks,

"Carbon chain" refers to the longest chain of carbon atoms in the molecule.

So 2,2,-dimethylhexane means that the longest carbon chain has 6 carbons (hexane) with two methyl groups both attached to the second carbon atom in the longest carbon chain. The molecule will have 8 carbon atoms altogether.

Also, for 7 atoms the number is "hept", so for your fourth molecule it is 4-methylheptane and not 4-methylseptane.

The one with the highest boiling point will most likely be 1,1,2,2,-tetramethylbutane. The one with the lowest b.p. will most likely be 4-methylheptane. (Though they are close calls)

All molecules have eight carbons...

You are incorrect. If you read my post above you will see why...