Answer:
A. East
Explanation:
There are 4 directions we use on a map: North, East, South, and West. Up and Down aren't relible directions to use if you are traveling somewhere.
I’m not fully sure but I think it’s
Cuba lies south of the Straits of Florida.
The ocean floor or seabed can be divided into three major regions: the continental margins, abyssal plains, and mid-ocean ridges.
Reindeer were domesticated almost 2000 years ago
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.
