I would say a. hope this helps
        
                    
             
        
        
        
<em>Answer: </em>tellurium (Te)
<em>atomic number = 52 ,</em>
<em>Number of energy levels = 5;</em>
               First energy level = 2
          Second energy level = 8
              Third energy level = 18
            Fourth energy level = 18
                Fifth energy level = 6
<em>In this electron configuration, 0uter most electrons are 6.</em>
 
        
                    
             
        
        
        
Explanation:
An perfect mass less spring, attached at one end and with a free mass attached at the other end, will have a distinct frequency of oscillation depending on its constant spring and mass. On the other hand, a spring with mass along its length will not have a characteristic frequency of oscillation. 
Alternatively, based on its spring constant and mass per length, it will now have a wave Speed. It would be possible to use all wavelengths and frequencies, as long as the component fλ= S, where S is the spring wave size. If that sounds like longitudinal waves, like solid sound waves.
 
        
             
        
        
        
Answer:
Control rods
Explanation:
Control rods is unique to nuclear power plants as they are mainly used in nuclear reactors to stabilize the rate of fission of plutonium or uranium. They are usually composed of chemical elements such as cadmium, silver, boron, and indium.
 
        
                    
             
        
        
        
you can find it using the equation: potential energy=mass*gravitational acceleration*height.
energy=50kg*9.8N/kg*40m=19600Nm=19600J or 19.6kJ
Sometimes they use 10 instead of 9.8 for the g constant. 
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