Answer:- 120 degree
Explanations:- In propene([tex]CH_2-CH=CH_2[/tex]) , we are asked to find out the C-C-C bond angle means the bond angle for the middle carbon. We know that carbon has 4 valence electrons in propene, the middle carbon is bonded to a hydrogen with a single bond, to one of the carbon with single bond and another carbon with a double bond.
Total number of bonds for the middle carbon is three and it has used all it's 4 electrons. So, it's geometry is trigonal planar and hence the C-C-C bond angle must be 120 degree.
