Answer:
Yes,
Explanation:
Africa is poor country. There are many people live with family so hard.American regions population ruch man.
Question: What is significant about the Han ethnic group in China?
Answer: About nine out of every ten Chinese people belong to this ethnic group.
Explanation: Han ethnic group comprises 92% of the Chinese population, and 19% of the world's people so the ethnic group is the dominant group
question answered by
(jacemorris04)
According to one hypothesis, life on earth emerged from (bluegreen algae/ amino acids/ molten metals/ crustal rocks) in the presence of large amounts of gasses seeping from deep ocean vents. ANother process called primordial soup suggests that the formation of life was due to the effects of (lightning/sunlight/gravity/meteorites) in earths atmosphere.
Answer:
B and C
Explanation:
B. In a given rock sample, the amount of Silicon-32 isotopes gets divided in half about every 170yrs.
This is the concept of half-life. Half life is the time take for half of a radioactive isotope to disintegrate. The shorter the half life the faster the isotope disintegrates.
From the question, we were told that it would take 170yrs for half of the isotope of Silicon to disintegrate to Phosphorus. This is the half life.
C. The half life can be used to determine the amount of Si-32 that has decayed from the time closure temperature was reached.
The closure temperature is very important in radioactivity. It is the temperature at which a system has cooled and there is no resulting disintegration of parent and daughter isotopes.
From first order kinetics, we know that the rate at which radioactive elements decay at any time is directly proportional to the number of radioactive atoms present. A knowledge of the half life helps to figure out the number of atoms that has decayed in time.
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