yaar

1.) octane no. is the reistance of a fuel to show knocking......( the jerk felt in combustion which lowers efficiency)......



octane no can be refferred to as the antiknocking property of the fuel

it ranges diff for diff fuels btw 0 - 100

0 being for n-heptane..

100 being for iso - octane



2.)i guess 3........

primarily bcoz it has 2 chiral centres and will hence rotate plane of polarised light accordingly twice each...so 3 enantiomers.....



correct me if i'm wrong on the second 1....

cheers