Which discovery by astronomer Vera Rubin helped prove the existence of dark matter?Which statement accurately describes the Doppler effect?

a and c are the answeres

population. population is the number of people or animals in a particular place. an example of population is over eight million people living in new york city.

here is your answer hope i .

the cost of mining is extremely low compared to the money earned from mining, creating income to improve the environment.

the answer is c. it will give up it's valence electron to the other atom.