(c) Specific charge on proton =$\left( \frac{e}{m} \right)_{p}$
=$9.6 \times 10^{7}C - {kg}^{- 1}$ specific charge on $\alpha$- particle,
$\left( \frac{q}{m} \right)_{\alpha} = \frac{2e}{4m} = \frac{1}{2}\left( \frac{e}{m} \right)_{p} = \frac{1}{2} \times 9.6 \times 10^{7}$
$= 4.8 \times 10^{7}\ C - {kg}^{- 1}$