Step-by-step explanation:
Formula for the capacitance of a parallel plate capacitor is as follows.
 C = 

where, A = area = 1 
 =
 = 

 d = diameter = 1 mm = 
 
 
 

Hence, putting the given values into the above formula as follows.
 C = 

 = 

 = 

Now, we will calculate the energy stored in the capacitor as follows.
 U = 

 = 

 = 

or, = 
 
 
Thus, we can conclude that energy stored on each capacitor is 
 .
.