Question

............... includes the largest fraction of petroleum crude.

• A. n-paraffin series
• B. Naphthene series
• C. Asphalts
• D. Isoparaffin series

Hint:

In crude oil classification, straight-chain paraffins (n-paraffins) dominate the lighter fractions and are most abundant by volume.

Answer 1

The Correct Option is A

Petroleum crude oil is a complex mixture of hydrocarbons, broadly categorized into different hydrocarbon series based on molecular structure. These include:
- Paraffins (alkanes)
- Naphthenes (cycloalkanes)
- Aromatics
- Asphaltenes and resins
Among these, the n-paraffin series (also known as normal alkanes) constitutes the largest fraction by volume in most types of crude oil. These straight-chain saturated hydrocarbons are typically found in light and medium crudes.
Naphthenes (cycloalkanes) are also present but in lower quantities than n-paraffins.
Isoparaffins are branched alkanes and are less abundant than their normal (straight-chain) counterparts.
Asphalts are heavy, complex, and non-volatile components, present in trace to moderate amounts and mostly in heavy crudes.
Therefore, the correct answer is n-paraffin series, as it includes the most significant proportion of hydrocarbons in crude oil.