MCQ Detailed View

Terrestrial planets are the four inner planets of the solar system: Mercury, Venus, Earth, and Mars. They are called “terrestrial” because they have solid, rocky surfaces similar to Earth. Unlike gas giants, which are mostly made of hydrogen and helium, terrestrial planets are primarily formed from rock and metal.

Each terrestrial planet has a dense, metallic core, usually made of iron and nickel. This core contributes to their gravity and, in planets like Earth, helps create a magnetic field. Above the core, there is a mantle and crust made mostly of silicate rocks. These rocks are rich in oxygen, silicon, magnesium, aluminum, and calcium.

The process of their formation explains their composition. During the early stages of the solar system, heavier elements like iron, nickel, and silicate minerals gathered closer to the Sun. Lighter gases were pushed farther away by strong solar winds, leading to the formation of gas giants in the outer solar system and rocky planets closer to the Sun.

For example:

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  Mercury: Has a large iron core and a thin rocky mantle.

  
  


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  Venus: A rocky planet with a thick atmosphere of carbon dioxide.

  
  


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  Earth: A solid surface of rocks, a metallic core, and abundant water.

  
  


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  Mars: A rocky planet with iron oxide on its surface, giving it a reddish color.

  
  

The correct answer is Both A and B because terrestrial planets are made of metals in their cores and rock on their outer layers. This solid structure is what makes them different from gas planets like Jupiter and Saturn, which do not have solid surfaces.

Understanding the composition of terrestrial planets is a key concept in everyday science, as it explains how planets form, why some are habitable, and what makes Earth unique in supporting life.