The answer to your question is A
An ethnic group can be classified as a community or population made up of people who share a common cultural background or descent.
Answer:
"Castro's relationship with Khrushchev appeared to be a threat to America's safety.
Kennedy attempted to create alliances with Cuba in order to overthrow the Soviet Union. "
Answer:
The rock is three million years.
Explanation:
First, we need to understand what half-life means. It is a period of time in which the radioactivity of the source decreases to the half of its original value ( the number of radioactive atoms decreases to half). We started off with 1000 atoms, which means that after one period of half time, the number will decrease to 500. So after million years we are left with 500 atoms. After another million years the number will decrease to 250 atoms. After the next half time period, the number will decrease to 125.
So:
1 half time: from 1000 to 500
2 half time: from 500 to 250
3 half time: from 250 to 125
So the number of atoms decreased from 1000 to 125 after 3 half time periods, which is after 3 million years.
