<span>Calcium - alkali earth metals is the answer</span>
        
             
        
        
        
Speed = frequency times wavelength.
40=8xf
f = 5 Hz or cycles per second.
        
             
        
        
        
The answer is attached. Also, you should know that the unit for acceleration is m/s2 and for velocity it is m/s.
 
        
        
        
Because the molecules that move freely begin to compact closer together, with less heat, means less molecular activity.