The wavenumber of the second line in the Paschen series of a hydrogen atom is: (RH = 1.097 × 10⁷ m⁻¹)
Paschen: n₁=3, second line n₂=5. ν̄ = 1.097×10⁷ (1/9 - 1/25) = 7.805×10⁵ m⁻¹.
Ref: NCERT Class 11 Chemistry > Chapter 2: Structure of Atom > Topic: Quantum Mechanical Model - de Broglie Heisenberg and Schrodinger