The mass of the ion is 5.96 X 10⁻²⁵ kg
Step-by-step explanation:
The electrical energy given to the ion Vq will be changed into kinetic energy

As the ion moves with velocity v in a magnetic field B then the magnetic Lorentz force Bqv will be balanced by centrifugal force
.
So,

and

Right from these eliminating v, we can derive

On substituting the value, we get:

m = 5.96 X 10⁻²⁵ kg.