A charged particle having drift velocity of 7.5 × 10^-4 m s^-1 in an electric field of 3 × 10^-10 Vm^-1, has a mobility in m^2 V^-1 s^-1 of:

A charged particle having drift velocity of $\displaystyle 7.5 \times 10^{-4} \mathrm{~m} \mathrm{~s}^{-1}$ in an electric field of $\displaystyle 3 \times 10^{-10} \mathrm{Vm}^{-1}$, has a mobility in $\displaystyle \mathrm{m}^2 \mathrm{~V}^{-1} \mathrm{~s}^{-1}$ of :