Select the correct statements :

            I) A proton and an alpha particle having the same kinetic energy are moving in circular paths in

            a uniform magnetic field. The radii of their circular paths will be equal.

            II) Any two charged particles having equal kinetic energies and entering a region of uniform

            magnetic field in a direction perpendicular to , will describe circular trajectories of equal

            radii.

            III) If a proton and an particle enter a uniform magnetic field perpendicularly, with the same

            speed, the time period of revolution of particle is double that of proton.

            IV) In a magnetic field, the time period of revolution of a charged particle is directly  

            proportional mass.