What was the composition of the Solar Nebula? 50% Rock, 50% Metal. 75% Gas, 25% Rock and Metal 98% Rock and Metal 1.4% Hydrogen and Helium, 0.6% Hydrogen Compounds. 98% Hydrogen and Helium, 1.4% Hydrogen Compounds and 0.6% Rock and Metal. (5 of 10) Where did the Terrestrial planets form? Beyond the Frost Line O Inside the Rock/Metal Condensation Line. Between the Rock/Metal Condensation Line and the Frost Line. None of the above.
The Correct Answer and Explanation is:
Correct Answers:
1. What was the composition of the Solar Nebula?
✅ 98% Hydrogen and Helium, 1.4% Hydrogen Compounds, and 0.6% Rock and Metal
2. Where did the Terrestrial planets form?
✅ Between the Rock/Metal Condensation Line and the Frost Line
Explanation
The Solar Nebula was the vast cloud of gas and dust from which our solar system formed about 4.6 billion years ago. It was composed primarily of light elements that are the most abundant in the universe, especially hydrogen (H) and helium (He). These two elements made up 98% of the nebula’s mass. The remaining 2% consisted of hydrogen compounds like water (H₂O), methane (CH₄), and ammonia (NH₃), along with rocks (silicates) and metals (like iron and nickel). Specifically, about 1.4% of the nebula was hydrogen compounds, and only 0.6% was rock and metal. These trace materials—though small in proportion—played a crucial role in forming the solid bodies of the solar system.
The terrestrial planets (Mercury, Venus, Earth, and Mars) formed between the Rock/Metal Condensation Line and the Frost Line in the early solar nebula. This zone was close enough to the Sun that it was too hot for volatile compounds like water, methane, and ammonia to condense into ice. However, it was cool enough for rock and metal grains to solidify. This region lies inside the Frost Line but beyond the Rock/Metal Condensation Line, where temperatures allowed the formation of solid rock and metal particles but not ices or gases.
Since only rock and metal could condense here, the terrestrial planets are rocky and dense, unlike the gas giants. Farther out, beyond the Frost Line, it was cold enough for ices to form, allowing the gas giants to build up massive cores and attract large gaseous envelopes.
Thus, the composition of the nebula and the temperature gradient determined where different types of planets formed, explaining the clear distinction between the rocky terrestrial planets and the gaseous outer planets.
