Question

Choose the force responsible for holding the atmosphere near the surface of earth.
A. Electrostatic force
B. Magnetic force
C. Frictional force
D. Gravitational force

Answer 1

We know that an atmosphere is a layer or a set of layers of gases surrounding a planet or other material body. So, the atmosphere of earth is the layer of gases surrounding our planet earth, the earth’s atmosphere is nitrogen $78\%$ and oxygen $21\%$ .

Complete step by step answer:
The earth’s atmosphere can be divided into layers based upon their temperature. These layers are the troposphere, the stratosphere, the mesosphere, and the thermosphere. There is also a layer around $500Km$ above earth’s surface which is called the exosphere.Earth’s atmosphere is only $\dfrac{1}{{1,200,000}}$ the mass of earth itself. So it’s very thin skin surrounding our planet. It’s gravity which holds our atmosphere to the surface of earth.

Gravitational force is an attraction force between two bodies and it is universal. It means it is a natural phenomenon by which all things with mass or energy including planet galaxies and even small bodies are attracted to each other. Escape velocity is the minimum velocity needed to escape the gravitational field. Hence, it’s the gravitational force which is responsible for holding the earth’s atmosphere near the surface of earth.

Hence, the correct answer is option D.

Note: Molecules in earth’s atmosphere is constantly moving and absorbing energy through sunlight and when they energized enough to get escape velocity which is equals to $11.2\,Km{\sec ^{ - 1}}$, such molecules can’t held by gravity and leave the surface of earth.