Answer:
I think we will know a lot more about the universe and the things around us. We may also know a lot more about other planets, such as Mars and Saturn, and we might also know a lot more about other stars in the universe.
Explanation:
I am not sure on number 1 but
2. Chemical Properties
3. Chemical reaction
4. Physical properties
5. Pure substance
Hope this helps!!
2 km since they walked 5km but then walked back 3km so it would be 5 - 3 = 2