#1
You used red pen highlight which made things messier
The correct name should be.
As a methyl group attached with 9th carbon
#2
methyl group at 4
double bond at 2
#3
Three methyl groups are present
Double bond at 2
- 2,5,5-Trimethyl Hex-2-ene
#4
- 2,5-Dimethyl Hept-3,5-diene
#5
2,5-Dimethyl Hex-3-ene