Question

which statement accurately describes the atmospheres of the inner planets?
mars has no atmosphere.
mercury has a thick atmosphere.
the atmospheres of mars and venus are similar in composition.
the atmospheres of earth and venus are similar in composition.

Explanation:

• Mars does have an atmosphere, so the first option is incorrect.
• Mercury has a very thin atmosphere (exosphere), not a thick one, so the second option is wrong.
• The atmosphere of Mars is about 95% carbon dioxide, and the atmosphere of Venus is about 96 - 97% carbon dioxide. So their atmospheres are similar in composition.
• The atmosphere of Earth is about 78% nitrogen, 21% oxygen, and small amounts of other gases. The atmosphere of Venus is mostly carbon dioxide. So they are not similar in composition.

Answer:

The atmospheres of Mars and Venus are similar in composition.