Answer:
1.23 m/s
Explanation:
p=mv
57.2 = 46.5v
v= 57.2/46.5
v= 1.23
If you want to verify your answer, just insert the value of v in the equation. 
 
        
             
        
        
        
Answer:E = hc/? = 4.41 x 10-19 J
Energy absorbed by each atom :
E (atom) = 2.205 x 10-19 J
Now Bond Energy of each molecule (B) = 3.98 x J
So, for each atom 1.99 x 10-19 J 
So now
KE of each atom = E(atom) - B (atom)
 = 2.15 x 10-19 J