Answer:
Heat
Step-by-step explanation:
An internal combustion engine convert a chemical energy to mechanical (kinetic) energy, which causes motion. the two types are: diesel powered or gasoline powered internal combustion engine. It has major applications in cars, trucks and vehicles.
Generally, internal combustion engines has a low efficiency due to some factors; rate of combustion, amount of available air etc. With the diesel engine having greater efficiency compared to that of gasoline engine.
According to thermodynamics, the remaining 70% would be dissipated to the surroundings in the form of heat.