Compared to lighter fractions, heavier fractions generally exhibit which of the following properties?

• A. All of the above
• B. Higher boiling points
• C. Greater viscosity
• D. Darker color

Answer: (D)

As the molecules in a fraction get larger and more complex, several properties change together. Heavier fractions have bigger, more intermolecular forces, which means they need more energy to boil. So, boiling points are higher. Larger molecules also don’t flow as easily, so viscosity increases. And with more extensive, longer chains and more aromatic content, these fractions absorb more visible light, making them appear darker.

Because all three properties—boiling point, viscosity, and color—tend to increase with heaviness, the best choice is the one stating all of the above. The option focusing only on darker color doesn’t capture the others.