In the revised Nebular Hypothesis proposed by Schmidt and Weizsäcker, the solar nebula was considered to be primarily composed of:

The correct option is Hydrogen and Helium.

Explanation

The Nebular Hypothesis is a theory concerning the origin of the Solar System. While originally proposed by Immanuel Kant and refined by Pierre-Simon Laplace, it underwent significant revision in 1950 by Otto Schmidt (Russia) and Carl Weizsäcker (Germany).

Detailed Analysis:

• Schmidt and Weizsäcker's Revision: They proposed that the Sun was surrounded by a solar nebula. According to their hypothesis, this nebula was primarily composed of Hydrogen and Helium, along with dust particles.
• Process of Formation: The hypothesis suggested that the friction and collision of particles within this cloud led to the formation of a disk-shaped cloud. Eventually, the planets were formed through the process of accretion.
• Comparison with other options: While elements like Iron, Nickel, Nitrogen, and Oxygen exist in the solar system, the primordial nebula described in this hypothesis was dominated by the universe's most abundant elements, Hydrogen and Helium.

Key Takeaway:

The revised Nebular Hypothesis by Schmidt and Weizsäcker posits that the primordial solar nebula consisted mainly of Hydrogen and Helium and dust.