JAMB - Chemistry (2007 - No. 35)
설명
An "anti-knock agent" for petrol (or gasoline) is a chemical additive that is added to fuel to prevent engine knocking, which is a knocking sound produced by premature ignition in the combustion chamber, and essentially increases the fuel's octane rating by delaying ignition.
Option A - 2,3- dimethylpentane
Option B - 3-methylhexane
Option C - 3-methylhexane
Option D - 2,2-dimethylpentane
Both 2,3-dimethylpentane and 2,2-dimethylpentane are branched-chain structures. However, 2,2-dimethylpentane has a more compact, highly branched structure, which is generally associated with higher octane ratings and better anti-knock properties.
In contrast, 2,3-dimethylpentane has a slightly less branched structure, which may result in slightly lower octane ratings. So, while both compounds are branched, the degree of branching and the resulting octane rating can differ.