Questions: Which statement describes the density of the inner planets? All the inner planets are dense. The inner planets are less dense than the outer planets. Earth is dense, while the other inner planets are not. Mercury and Venus are dense, while Earth and Mars are not.

The answer is the first one: All the inner planets are dense.

Explanation for each option:

1. All the inner planets are dense.

   • This statement is correct. The inner planets, also known as terrestrial planets (Mercury, Venus, Earth, and Mars), are composed primarily of rock and metal, making them denser than the outer planets, which are mostly composed of gases and ices.

2. The inner planets are less dense than the outer planets.

   • This statement is incorrect. The inner planets are denser than the outer planets. The outer planets, or gas giants, have a lower density because they are composed mainly of hydrogen, helium, and other gases.

3. Earth is dense, while the other inner planets are not.

   • This statement is incorrect. While Earth is indeed dense, the other inner planets (Mercury, Venus, and Mars) are also dense compared to the outer planets.

4. Mercury and Venus are dense, while Earth and Mars are not.

   • This statement is incorrect. All the inner planets, including Earth and Mars, are dense. Earth is actually the densest planet in the solar system.

In summary, the inner planets are all dense, which is a characteristic feature distinguishing them from the less dense outer planets.