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

Question

If the shortest wavelength in Lyman series of hydrogen atom is A , then the longest wavelength in Paschen series of He + is, 5 A 9, 36 A 7, 36 A 5, 9 A 5

MARKS App · Accepted Answer

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 .

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