We know that it is a certainty based on things such as the size, mass, brightness, etc. They can determine to within a relative level of accuracy the age. Of course they can be off by millions of years, but that’s pretty precise for a 10–20 billion year time period for the life of a star. BUT we absolutely cannot predict exactly when it will explode and we see supernovas in other galaxies, but the last one in the Milky Way that we observed was in the 1600s.
Answer:
I believe that it is C. An area where the water table slopes toward a well.
Explanation:
2 and 5 are features of sexual reproduction.
Answer:
D. Asexual reproduction
Explanation:
In the process of asexual reproduction a new organism is produced from a single parent organism. So the new offspring inherits all the genetic traits of a single parent, there is no recombination of genetic traits. However, in sexual reproduction there is recombination of genetic traits so the offspring shows genetic variation.
The number of neutrons=Atomic mass-atomic number
no of neutrons=20-10
no of neutrons=10