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:
Explanation:
A lifeboat is a boat, specially made to move from land to sea to help people who are in difficulty. Garrett James Hardin, an American environmentalist uses this description of lifeboat to warn of the dangers of human overpopulation which does not only affect the populated nations but everyone. The rich people (mostly the Americans) are the ones in the lifeboats, and the poor ones are in the waters swimming and trying to board any of the lifeboats. The nations who are like lifeboats have a specific-carrying capacity (or limited amount) that should not be exceeded.
If there are fifty people in the lifeboats with ten free spaces that could be given to hundred poor people waiting to be saved, further explanations were offered by Hardin on what to be done. Allowing everyone in, which would mean hundred and fifty people are in the boat at the same time could make it sink. The ten spaces could be offered on who arrives first or the best ten from the hundred poor people could be allowed to come on board. There are some people, among the lucky fifty rich people who would feel guilty according to Hardin, that the remaining ninety could die and so they are willing to give-up their spaces for the less fortunate ones. The best solution would be for no one to be allowed into the boat, preserving the lucky fifty from sinking with the boat as stated by Hardin.
Nations are not actually lifeboats and the human race have grown beyond being measured to have a limited number of persons it can contain as stated by Hardin. The possible maximum number of persons a particular area can contain should never be important to mankind where there is a terrible event affecting human beings. Also the lucky fifty in the lifeboats may think they are safe, but they could be affected by a huge wave in the sea that would make the entire lifeboat nations to drown.
Indian ocean
Atlantic ocean
pacific ocean
Answer:
Intrusi magma
Explanation:
Intrusi magma dapat memberikan manfaat bagi manusia sebab magma ini ketika keluar menuju permukaan bumi akan menjadi gunung berapi, yang bermanfaat karena menghasilkan tanah vulkanik yang subur. ... Lava dan abu vulkanik dari letusan akan terurai dan menghasilkan nutrisi yang penting bagi tanah
