<span>The answer is Due to heating of the air by the engine exhaust. Contrails are formed when the hot exhaust of the plane engines is rapidly cooled by the cold air in the upper atmosphere. The water vapor in the engine exhaust, formed in the combustion of fuel, freezes immediately to ice crystals due to the low pressure and -36oC temperatures in the 8000 m altitude in which the planes cruise. </span>
with this option given I don't think there is an odd one
Answer:
6 and 6
Explanation:
All elements have an equal number of protons and neutrons