Final answer:
Correct comparisons between Earth and Mars include them having similar lengths of a day and the existence of water on both. However, they have different masses, atmospheric compositions, and Earth has a global magnetic field unlike Mars.
Step-by-step explanation:
When comparing Earth and Mars, it's important to address the correct statements from your choices:
- (a) They have approximately the same length of day. This is true. A day on Mars is slightly longer than a day on Earth, approximately 24 hours and 37 minutes.
- (b) They have approximately the same mass. This is false. Mars has a mass only about 0.11 times that of Earth, making it significantly smaller.
- (c) They have approximately the same atmospheric composition. This is false. The atmospheres are quite different, with Earth's atmosphere rich in nitrogen and oxygen, while Mars has a thin atmosphere, primarily composed of carbon dioxide.
- (d) Water is present on both their surfaces. This is true. While Earth has liquid water on its surface, Mars has water in the form of ice, and possibly transient briny flows.
- (e) Both planets have strong magnetic fields. This is false. Earth has a global magnetic field, while Mars does not have a global magnetic field currently, though local magnetic fields exist in its crust.
Overall, the true comparisons between Earth and Mars are related to the length of their days and the presence of water in some form on both planets.