Question

draw the structural formula for 2-methyl-3-octene
and the 3 isomers of pentane

Answer 1

so first draw the backbone 3-octene

Answer 2

you know that the main chain is 8 carbons long and the double bond (ene) is on the third carbon

Answer 3

what does the 2 stand for?

Answer 4

now add the side chains