The frequency corresponding to transition n = 2 to n = 1 in hydrogen atom is

v¯=1λ=R1n12−1n22=10967811−14=82258.5λ=1.21567×10−5cm or λ=12.1567×10−6cm=12.1567×10−8mv=cλ=3×10812.1567×10−8=24.66×1014Hz