<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:
The heat transfers from the air of higher temperature to the can which has lower temperature.
Explanation:
In thermodynamics, heat is the transfer of energy from a higher temp to a lower temp.
 
        
             
        
        
        
We eat and drink to obtain the energy and matter we use to survive
        
                    
             
        
        
        
I guess you forgot to add the picture or so.
Based on the Complementarity of the 4 nucleotides, The thymine must always be placed in  front of the Adenine, and the Cytosine must always be placed in front of the Guanine. 
Any change in this rule causes the deformation of the DNA, and can sometimes cause fatal diseases like the melanoma (skin cancer) etc...
Hope this Helps! :)
        
             
        
        
        
It’s nitrogen! Hope this helps