Kerosene quality is judged strongly by clean burning and high smoke point. Among i-paraffins (iso-paraffins), aromatics, n-paraffins, and naphthenes, select the most desirable hydrocarbon family for good quality kerosene.

Introduction / Context:
Kerosene performance in lamps and jet/household uses is tied to smoke point and combustion cleanliness. Hydrocarbon family composition influences smoke formation, odor, and stability. This item asks which family is most desirable overall for kerosene quality.

Given Data / Assumptions:

• Families considered: n-paraffins, i-paraffins, aromatics, naphthenes.
• Quality metric emphasized: smoke point/clean burning behavior.
• Normal handling and storage conditions implied.

Concept / Approach:
Aromatics generally depress smoke point and are undesirable for kerosene burning quality. Paraffins (normal and iso) and naphthenes burn cleaner; among these, naphthenes are widely cited as desirable for kerosene because they help deliver higher smoke points and good combustion stability relative to aromatics. (Note: exact optimal mix depends on multiple specs; aromatics are clearly least desirable.)

Step-by-Step Solution:

Verification / Alternative check:
Refining texts link high smoke point kerosenes to lower aromatics and adequate naphthenic/paraffinic content; naphthenes are often favored for lamp-burning properties.

Why Other Options Are Wrong:

Common Pitfalls:
Assuming octane-related reasoning applies; kerosene quality focuses on smoke point, not spark-ignition octane.

Final Answer:
Naphthenes