AVTUR is heavier than AVGAS because

• A. It has higher energy content per unit mass
• B. It has higher energy content per unit volume
• C. It has higher density
• D. It evaporates at a higher temperature

Answer: (B)

The main idea here is energy density by volume—the amount of energy stored in each liter of fuel. AVTUR (jet fuel) delivers more energy per liter than AVGAS. That higher energy per unit volume comes from AVTUR’s combination of density and energy-per-mass characteristics, so in a given liter you’re carrying more energy, which is why it’s described as heavier per unit volume. In numbers, AVTUR’s density is higher than AVGAS and its energy per kilogram is similar or slightly lower, but the result is that a liter of AVTUR contains more energy overall than a liter of AVGAS, making AVTUR heavier when compared by volume. The other options aren’t the right fit because evaporation temperature or energy per mass alone don’t explain why a liter of AVTUR weighs more or carries more energy per liter in practice.