4/3 m/s ( approximately 1.3333... m/s)
Every point on the surface must have the same rotational speed.
Otherwise some places would rotate away from other places.
If the next block of your city rotated faster than the block that you live on,
then you could sit at home, look out the window, and watch your school
rotate past your house.
The map of the continents on the Earth would change constantly.
The mass of the ion is 5.96 X 10⁻²⁵ kg
<u>Explanation:</u>
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.
The correct answer is B. Nitrogen