Question

A hydrocarbon consists of four carbon atoms with one double bond. Predict the molecular formula of this compound. which one is it please help
C4H8
C4H10
C4H4
C4H6

Answer 1

The first one, C4H8. Maybe it's easier for you to see why if you draw the structure of the hydrocarbon described? Remember that a carbon can form four bonds with other atoms.

So, does this drawing make sense to you? (And the double bond wouldn't necessarily need to be at the last two carbon atoms, it might as well be in the middle - the number of hydrogen atoms would have been the same anyway.)

Answer 2

Thank you and yea it helps.