Question

How many of the carbon-carbon double bonds in lycopene have the possibility for cis-trans isomerism ?
plz help

Answer 1

13. Look at it's IUPAC nomenclature.

Answer 2

This question is rather odd. The answer depends on whether you would include EZ geometric isomers. All 13 double bonds (2 or 3 substituent groups) have EZ isomers while 5 double bonds show only cis-trans isomerism (2 substituent groups). Check the structure of lycopene here on wikipedia:
http://en.wikipedia.org/wiki/Lycopene