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.
Answer:
At the boundary with the core.
Explanation:
The mantle is the second layer from the top. It is bordered by the lithosphere above it, or rather by the crust, and by the outer core below it. The mantle is a layer which is in viscous state, being mostly consisted of molten metals and rocks. The temperature of this layer is not the same all throughout it, but it varies a lot. The temperature at its top part is around 200 C degrees, while the temperature at its bottom is around 4,000 C degrees. There's two reasons for this. One is that the core is very hot, so it makes the bottom part of the mantle very hot as well, and the other one is that the lithosphere is much cooler, as well as constantly getting new, cold, crust in it, which makes its top part much cooler. The mantle is the layer responsible for the movement of the tectonic plates on the surface, as it is the layer where the convection currents occur and drive the plates' movement.
Answer:
The Goode homolosine projection (or interrupted Goode homolosine projection) is a pseudocylindrical, equal-area, composite map projection used for world maps. Normally it is presented with multiple interruptions. Its equal-area property makes it useful for presenting spatial distribution of phenomena.
Explanation:
The Goode homolosine projection (or interrupted Goode homolosine projection) is a pseudocylindrical, equal-area, composite map projection used for world maps. Normally it is presented with multiple interruptions. Its equal-area property makes it useful for presenting spatial distribution of phenomena.
Answer:
Correct answer is The US had a capitalist system, and the USSR had a communist system.
Explanation:
First option is not correct as democracy is a political, not economical system.
Second option is not correct, as United States fought against Socialism and Communism.
Third option is correct because Soviet Union had communist system, which included expropriation of land, while States developed Capitalism.
Last option is also not correct, due to facts mentioned before.
<span>cirrus, altocumulus, stratus</span>
