Aniline point of high-speed diesel (HSD): choose the approximate value (in °C) most commonly cited for typical diesel fuels.

Introduction:
The aniline point is a quick indicator of a fuel’s aromatic content and solvency. For diesel fuels, it correlates loosely (inversely) with aromaticity: higher aniline point implies more paraffinic character. Typical values help blenders and inspectors assess whether a diesel is unusually aromatic or paraffinic.

Given Data / Assumptions:

• Fuel: high-speed diesel (HSD) in normal market ranges.
• Aniline point definition: minimum temperature at which equal volumes of aniline and the fuel are completely miscible.
• We seek a representative value rather than an extreme.

Concept / Approach:
Common diesel aniline points are around the range of 60–90 °C depending on crude source and processing. A textbook, rule-of-thumb figure often quoted is about 70 °C for typical HSD. Lower values would suggest unusually aromatic diesel; very high values indicate exceptionally paraffinic material.

Step-by-Step Solution:
1) Recall the typical range for diesel aniline points.2) Identify 70 °C as a central, representative value.3) Select 70 °C among the choices.

Verification / Alternative check:
Specification references and educational tables frequently use 70 °C as an indicative value in example problems and quick-look properties.

Why Other Options Are Wrong:
35: Too low for typical diesel; suggests highly aromatic character.105 or 150: Unusually high for standard HSD.20: Not realistic for diesel.

Common Pitfalls:
Confusing gasoline (generally not assessed by aniline point) with diesel/kerosene where the property is commonly referenced.

Final Answer:
70