ANS:B - Aromatics

Among the options provided, Aromatics are desirable in petrol (gasoline) but undesirable in kerosene. Here’s why:

• Paraffins: These are straight-chain or branched hydrocarbons that burn cleanly and contribute to the octane rating of gasoline. They are generally desirable in both petrol (gasoline) and kerosene.
• Aromatics: These hydrocarbons have a ring-like structure and are more resistant to combustion, contributing to the octane rating of gasoline but can lead to increased emissions and air pollution. They are desirable in petrol (gasoline) for their high octane rating but are undesirable in kerosene due to their lower combustion efficiency.
• Mercaptans: These are sulfur-containing compounds that impart an unpleasant odor to fuels. They are undesirable in both petrol (gasoline) and kerosene.
• Naphthenic acids: These are not typically found in significant amounts in either petrol (gasoline) or kerosene. They are acids and would generally be undesirable in fuels due to potential corrosive effects.