The number of spectral lines produced when an electron in a hydrogen atom falls from n = 5 to n = 2 is:
Transitions: 5→2, 5→3→2, 5→4→2, 4→2, 3→2. Total = 5.
Ref: NCERT Class 11 Chemistry > Chapter 2: Structure of Atom > Topic: Shapes of Orbitals - s p d f and Nodes and Radial Probability