The correct option is 2 only
Explanation
Early theories regarding the origin of the earth and the solar system primarily revolve around the Nebular Hypothesis. This theory attempts to explain how the planets and the sun formed from a primordial cloud of gas and dust.
Statement 1 is Incorrect:
The Nebular Hypothesis was one of the earliest popular arguments regarding the earth's origin. It was first proposed by the German philosopher Immanuel Kant. The theory was later revised by the mathematician Laplace in 1796. It postulated that planets formed out of a cloud of material associated with a slowly rotating youthful sun.
Statement 2 is Correct:
In 1950, Otto Schmidt (Russia) and Carl Weizascar (Germany) revised the nebular hypothesis. They suggested that the sun was surrounded by a solar nebula consisting mostly of hydrogen and helium along with dust. The statement incorrectly mentions nitrogen and oxygen as the primary constituents.
Statement 3 is Incorrect:
The revised hypothesis by Schmidt and Weizascar proposed that the friction and collision of particles led to the formation of a disk-shaped cloud and the planets were formed through the process of accretion. Degassing is the process responsible for the formation of the atmosphere (release of gases from the interior), not the formation of the planets themselves.
Key Takeaway:
The Nebular Hypothesis, initiated by Kant and Laplace, explains planetary formation from a rotating cloud. Later revisions by Schmidt and Weizascar identified the nebula's composition as hydrogen and helium and attributed planetary formation to the process of accretion.