A charge $q,$ mass $m,$ travelling with speed $v$ enters a region of magnetic field at an angle $\theta$ with magnetic field. Mark the following statements as true or false.

$\left(\mathrm{a}\right)$ Kinetic energy of particle remains constant irrespective of $\theta$

$\left(\mathrm{b}\right)$ Velocity of particle remains constant if $\theta =n\pi ,$ where $n$ is an integer

$\left(\mathrm{c}\right)$ Speed of particle remains constant

$\left(\mathrm{d}\right)$ Acceleration of particle remains constant if $\theta =\left(2n-1\right)\frac{\pi }{2}$

$\left(\mathrm{e}\right)$ Average velocity of particle becomes negligible if $\theta =\left(2n-1\right)\frac{\pi }{2}$ over a long time