Step 1: Use Bohrâs formula for electron velocity.
The velocity of an electron in a particular orbit is inversely proportional to the square root of the principal quantum number \( n \), i.e.,
\[
v_n \propto \frac{1}{\sqrt{n}}
\]
Step 2: Calculate the velocity ratio.
For the second orbit (\( n = 2 \)) and the fifth orbit (\( n = 5 \)), the ratio of velocities is:
\[
\frac{v_5}{v_2} = \frac{\sqrt{2}}{\sqrt{5}} = \frac{2}{5}
\]
Step 3: Conclusion.
Thus, the velocity of the electron in the fifth orbit is \( \frac{2}{5}v \).