$\frac{e}{m}=1.76 \times 10^{11}\, \mathrm{C\,kg}^{-1}$

Frequency of revolution of the electron,

$v=\frac{1}{T}=\frac{v}{2 \pi r}.........(i)$

Also, $\frac{m v^{2}}{r}=e v B \Rightarrow \frac{v}{r}=\frac{e B}{m}.........(ii)$

From eqns. $(i)$ and $(ii)$,

$v=\frac{1}{2 \pi} \times \frac{e B}{m}=\frac{1}{2 \times 3.14} \times 1.76 \times 10^{11} \times 3.57 \times 10^{-2}$

$=10^{9} \,\mathrm{Hz}=1 \,\mathrm{GHz}$