IMAT 2016 Q49 (Chemistry)

Does anyone have a diagram for the different molecules? I got 10 options but the answer is 9 (B). Thanks in advance!

How many unbranched straight chain molecules are there with the molecular formula C4H8F2 but with different structural formulas?

A 8
B 4
C 9
D 12
E 6

Hi! I think there’s a mistake in the answer. The mark scheme of this paper tells me that the answer is 6 which is right! Note the question asks for unbranched molecules! Here’s the diagram



Hey! I have one question, do you think the best way/fastest way of finding the max number of isomers is by drawing each one and too see if they have different nomenclatures (to check there are no repeated structures)? It always take me some time to draw all of the isomers so I would love to know if there’s a shortcut :ok_woman:

hiii, sadly if it’s not a hydrocarbon, I only know that the way is to draw them so maybe leave them till the end. For hydrocarbons you can use the formula 2^(n-4)+1 to calculate the possible structural isomers where n is the number of carbons. @dorsa_vaezi helped me with this. Is it for alkanes, alkenes or both??