<span>Answer: a. take place in nuclear reactors
</span><span>Controlled nuclear chain reactions are the reaction in nuclear reactors. The reaction is controlled to make its rate slower. This will make the reaction relatively safer, so the energy produced can be changed into electricity in power plant. When the reaction is not controlled, it could cause explosive like in nuclear bomb.</span>
Answer : A metal in group 16 of the periodic table can become a chemically stable ion by gaining 2 electrons.
Explanation :
The group 16 element are oxygen, sulfur, selenium, tellurium and polonium.
The general electronic configuration of group 16 elements is, 
As we now that there are total 6 electrons in p sub-shell. So, a metal in group 16 can become a chemically stable ion by gaining 2 electrons.
Hence, a metal in group 16 of the periodic table can become a chemically stable ion by gaining 2 electrons.
Answer:
La vejiga natatoria en un pez, se ve afectada por la presión hidrostatica del agua, generando presión y estrechamiento sobre esta, al disminuirse hace más fácil la inmersión, puesto que está vejiga contiene aire que tiene peso menor que el agua y hace flotar con más facilidad al pez, sin embargo cuando el pez sube, la vejiga aumentará su volumen y tendrá que nadar más para mantenerse más abajo en el agua
Answer: c. Air pollution
Explanation:
There was a heatwave in Europe during the early years of the 21st century that killed tens of thousands across the continent and thousands in France.
Air pollution was blamed for having made the situation worse because the pollutants in the air acted to prevent heat from escaping back into the atmosphere which led to increased heat on ground and therefore a heat wave.
