EVERYDAY SCIENCE

Detailed explanation-1: -The exosphere layer is mainly composed of extremely low densities of hydrogen, helium and several heavier molecules including nitrogen, oxygen and carbon dioxide closer to the exobase. The atoms and molecules are so far apart that they can travel hundreds of kilometers without colliding with one another.

Detailed explanation-2: -The thermosphere is the thickest layer in the atmosphere. Only the lightest gases-mostly oxygen, helium, and hydrogen-are found here. The thermosphere extends from the mesopause (the upper boundary of the mesosphere) to 690 kilometers (429 miles) above the surface of the Earth.

Detailed explanation-3: -Answer. Because of their low molecular weight, they can be easily escape from the atmosphere. So, they are found in exosphere.

Detailed explanation-4: -Exosphere Facts It is the first layer to shield the Earth from meteors, asteroids, and cosmic rays. The temperature of the exosphere varies dramatically. The temperature is lower at night and much higher during the day. The exosphere’s air is very thin and mainly composed of helium and hydrogen.