Answer:
20
Explanation:
number of protons+ number of neutrons= mass of atom
19+n=39
n=39-19=20
number of neutrons=20
What i really think is that when only Russia Russia did not exist, then i am sure that no one would even know the history from there. so the answer to this would be that when Russia was existing, then only that is when the date roots come from. i hope that this helps you. have a great day! =)
<u>Question: Why do political boundaries change?</u>
<u />
Answer: <u>These lines, more often called borders, are created by people to separate areas governed by different groups. Sometimes, political boundaries follow physical boundaries, but most of the time you can't see them. Most maps show political boundaries. Political boundaries change over time through wars, treaties, and trade.</u>
<em>Hope this helps!</em>
<em>~~~~~~~~~</em>
<em>~A.W~ZoomZoom44</em>
Constructive plate boundaries
1) Convection currents in the mantle move the plates
2) 2 plates of oceanic crust diverge/pull apart e.g. North American and Eurasian plates.
3)
The rising magma forces the ends of the plate to push up and buckle.
This creates tensional cracks on the underside of the plates.
4) Magma is squeezed into the gap between the two plates and is cooled by the ocean to form new, solidified rock/basalt.
5) Rising magma forces its way through the tensional cracks and forms sub-marine shield volcanoes on the ocean floor.
6)
With repeated eruptions over millions of years they can grow until
they break the surface of the ocean and become volcanic islands e.g.
Iceland.
There ethnic was wavered after most of them were wiped out