Answer:
Part a)

Part b)

Part c)
d = 0.072 m
Step-by-step explanation:
Part a)
As we know that the radius of the charge particle in constant magnetic field is given by

now for single ionized we have


Part b)
Similarly for doubly ionized ion we will have the same equation



Part c)
The distance between the two particles are half of the loop will be given as


