Which of the following helps keep Earth's atmosphere in place?

Gravitational force of Earth

The correct answer is Option (3) - Gravitational force of Earth

The Earth's atmosphere is held in place primarily by the gravitational force exerted by Earth. Gravity is the force that attracts objects towards the center of the Earth, including the gases that make up the atmosphere. As a result, the gases comprising the atmosphere are bound to Earth's surface by gravity.

Additionally, the rotation of Earth on its axis also plays a crucial role in maintaining the stability of the atmosphere. The rotation creates centrifugal force, which tends to push air away from the Earth's surface. However, gravity counteracts this force, preventing the atmosphere from being stripped away into space.

Overall, it's the combined effect of gravity and Earth's rotation that helps to keep the atmosphere in place, ensuring that the gases remain bound to the planet and creating the conditions necessary for life to thrive.