The radius of the second orbit of a hydrogen atom is 2.116 × 10⁻¹⁰ m. What is the velocity of the electron in the fourth
v₄ = v₁/4 = 5.475×10⁵ m s⁻¹.
Ref: NCERT Class 11 Chemistry > Chapter 2: Structure of Atom > Topic: Electronic Configuration - Aufbau Pauli Hund and Stability