(a) Charge on nucleus
$\mathcal{Q =}Ze = 47 \times 1.6 \times 10^{- 19}$
$= 7.52 \times 10^{- 18}C$
Potential on the surface of nucleus is
$V = \frac{1}{4\pi\varepsilon_{0}}\frac{\mathcal{Q}}{r}$
$= \frac{9 \times 10^{9} \times 7.52 \times 10^{- 18}}{3.4 \times 10^{- 14}} = 1.99 \times 10^{6}V$