Question

which statement is true?
inner and outer planet composition supports the nebular theory because heavier elements condense close to the sun, and lighter elements condense at cooler temperatures.
nuclear fusion occurs at cooler temperatures, away from the sun.
the inner planets are gas giants, and the outer planets are rocky.
the big bang is a theory about the origin of the solar system.

Explanation:

• Analyze the first option: The nebular theory states that in the solar nebula, heavier elements (which condense at higher temperatures) formed the inner rocky planets, and lighter elements (condensing at cooler temperatures farther from the Sun) formed the outer gas giants. This matches the first statement.
• Analyze the second option: Nuclear fusion requires extremely high temperatures and pressures, which occur in the Sun's core, not at cooler temperatures away from the Sun. So this is false.
• Analyze the third option: Inner planets (Mercury, Venus, Earth, Mars) are rocky, outer planets (Jupiter, Saturn, etc.) are gas giants. This statement reverses them, so it's false.
• Analyze the fourth option: The Big Bang theory explains the origin of the universe, while the nebular theory explains the origin of the solar system. So this is false.

Answer:

The true statement is: Inner and outer planet composition supports the nebular theory because heavier elements condense close to the Sun, and lighter elements condense at cooler temperatures.