Regarding the specific gravity of Jet Fuel, calorific value per kilogram increases as SG increases.

• A. Calorific value per kilogram increases as SG increases
• B. Calorific value per kilogram decreases as SG increases
• C. Calorific value per kilogram remains constant with SG
• D. Calorific value per kilogram varies unpredictably with SG

Answer: (A)

The key idea is how the energy content per unit mass (calorific value per kilogram) relates to how dense the fuel is (specific gravity). In aviation fuels, higher SG means the average molecule is heavier and typically more energy-packed. Heavier hydrocarbons store more chemical energy per mole, and when you have more mass in the same volume, you also tend to have more energy per kilogram. So as SG increases within the typical Jet fuel range, the calorific value per kilogram tends to rise. This aligns with Jet A-1 being around 43 MJ/kg, while the density is about 0.80 kg/L, and a modest increase in density reflects a slight increase in energy per kilogram. While other factors like impurities can tweak the exact numbers, the general trend is that higher SG corresponds to higher calorific value per kilogram, making the statement the best fit among the choices.