Answer:
3. we would not exist because we are made of material that was recycled in galaxies.
Explanation:
If stars are randomly distributed in space, the elements like Hydrogen, Nitrogen, etc that releases when stars are dieing will not be close enough to come together to form a planet and thus lead to the formation of life on Earth.
Answer:
3 half live have passed.
Explanation:
After 1 half-life , 500 g of the parent isotope will remain. After 2 half-lives , 250 g of the parent isotope will remain. After 3 half-lives , 125 g of the parent isotope will remain.
