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.
C, cause the sail actually gave more crew men jobs, also adding members to ships, employing more people
Answer:
Over time people move to other places depending on their opportunities.
Explanation: If someone wanted to be a farmer they would settle down in a more fertile area where they can get more land. and someone who wants to be a lawyer or doctor would settle in a more busy area in the city.
Answer:
Soil(i) -the unconsolidated mineral or organic material on the immediate surface of the Earth that serves as a natural medium for the growth of land plants.
Rocks(in)- is any naturally occurring solid mass or aggregate of minerals or mineraloid matter.
Explanation:
hope it helps
Magnetic declination, or magnetic variation, is the angle on the horizontal plane between magnetic north and true north. This angle varies depending on position on the Earth's surface and changes over time
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~its Srishty~✿
