Answer:
(a) 
(b) 
(c) 
Solution:
As per the question:
Radius of the orbit, 
Mass of an electron,
Now,
To calculate the radial acceleration, force due to the acceleration of the electron is balanced by the electrostatic force:
(1)
where


Since, the charge particles are electrons, thus:

where
k = electrostatic constant = 
Use eqn (1):


where
a = radial acceleration
e = charge on an electron = 
Therefore,

a = 
(b) To calculate the speed, 'v' of an electron in the circular orbit:
Here, the force is given by the centripetal force:




(c) To calculate the period:

where
= angular velocity
Thus


