Question

Percentage of Oxygen in the Earth’s atmosphere is _______
a. 21%
b. 78%
c. 20.94%
d. 10%

Answer 1

Hint: The atmosphere is a layer of gases present around the earth. It is made up of numerous gases, but the major gases are nitrogen and oxygen, present in large amounts. The presence of breathable oxygen in the atmosphere is essential for life on earth.

Step by step answer:
 The Atmosphere is the gaseous cover over the earth’s surface consisting of gases like Nitrogen, Oxygen, Argon, Carbon Di-Oxide, and a few others. The percentage of the above-mentioned gases with respect to their volume in the atmosphere is 78%, 20.94%, 0.934%, and 0.038%. respectively. There are trace amounts of other gases like Neon, Helium, Methane, Krypton, and Hydrogen. The atmosphere of the Earth is made up of five distinct layers. They are the troposphere, closest to the earth’s surface. The stratosphere comes above the troposphere, and then comes the mesosphere. Above it, there is the thermosphere and the last one is the exosphere. The atmospheric pressure drops as one travels from the troposphere to the exosphere. The earth is able to support life only because of the presence of the atmosphere. The composition of the atmosphere keeps the earth warm enough for water to exist in the liquid state as necessary for living things. There is also Ozone in the atmosphere which protects the earth from harmful UV rays coming from the Sun.

So, the correct answer is

Note The ecosystem consists of 4 spheres. The atmosphere is made up of air. The hydrosphere is made of water, the lithosphere made up of solid ground and the biosphere consists of the life forms present on the earth.