If the shortest wavelength in Lyman series of hydrogen atom is A , then the longest wavelength in Paschen series of He + is

Step-by-step solution

1 λ = R H × ( Z ) 2   1 n 1 2 − 1 n 2 2 Shortest wavelength for Lyman series of H   atom n 1 = 1 (Lyman series) n 2 = ∞ SO, 1 λ 1 = 1 × R H 1 1 − 1 ∞ λ 1 = 1 R H = A    ∴ λ = A longest wavelength for Paschen series of He + atom n 1 = 3 n 2 = 4 1 λ 2 = ( 2 ) 2 × R H   1 ( 3 ) 2 − 1 ( 4 ) 2 1 λ 2 = 4 × R H   7 9 × 16 = R × 7 36 λ 2 = 36 7 R H = 36 7 A .