3. Hydrogen content in petroleum products varies from 12 to 15% (by weight). As a result the difference between gross and net heating value of petroleum fuels varies in the range of __________ kcal/kg.
7. Raw Kerosene has a smoke point of 15 mm. After it is subjected to dearomatisation by liquid SO2 extraction (Edeleanu process), its smoke point may become __________ mm.