Answer
$v=1.09 \times 10^6 m/s$
Work Step by Step
The radius of second smallest orbit is
$r_2 = 2^2a_o = 4(5.292 \times 10^{-11} m) = 2.12 \times 10^{-10} m $
$v= \sqrt{\frac{k|e|^2}{m_er} }$
$v= \sqrt{\frac{(8.99 \times 10^9 N . m^2 / C^2) (1.6 \times 10^{-19}C)^2}{(9.11 \times 10^{-31} kg )(2.12 \times 10^{-10} m)} }$
$v=1.09 \times 10^6 m/s$
