Co carbon monoxide
sorry friend i don't know other ones
        
             
        
        
        
Answer:
The answer is 0.5 Hz 
Explanation:
Its pretty easy to get the answer. One hertz (Hz) is equal to one cycle or period per second. So, just divide the period by the number of seconds.
1 period/2 secs = 1/2 Hz or 0.5 Hz
 
        
             
        
        
        
<span>A: put an atom on a poster in the exhibit 
     Good luck.  The poster itself is made of trillions of trillions of trillions 
     of atoms.  You could not see the extra one any easier than you could
     see the ones that are already there, and even if you could, it would be 
     lost in the crowd.
 
B: use a life size drawing of an atom 
     Good luck.  Nobody has ever seen an atom.  Atoms are too small 
     to see.  That's a big part of the reason that nobody knew they exist 
     until less than 200 years ago. 
D: set up a microscope so that visitors can view atoms
     Good luck.  Atoms are way too small to see with a microscope.
</span><span><span>C: Display a large three dimensional model of an atom.
    </span> </span>Finally !  A suggestion that makes sense.
     If something is too big or too small to see, show a model of it 
         that's just the right size to see.