The velocity of an electron in the second orbit of sodium atom (atomic number = 11) is v. The velocity of an electron in its fifth orbit will be
Answer & explanation
Correct answer: option 4
$v_n \propto \frac{1}{n} \Rightarrow \frac{v_5}{v_2}=\frac{2}{5} \Rightarrow v_5=\frac{2}{5} v_2=\frac{2}{5} v$