For He + , a transition takes place from the orbit of radius 105 . 8 pm to the orbit of radius 26 . 45 pm . The wavelength (in nm ) of the emitted photon during the transition is Bohr radius, a = 52 . 9   pm Rydberg constant, R H = 2 . 2 × 10 - 18   J Planck's constant, h = 6 . 6 × 10 - 34 Js Speed of light, c = 3 × 10 8   ms - 1 ]
A. A
The radius of the n th orbit can be represented as, r = 52 . 9 × n 2 z pm ∴    105 . 8 = 52 . 9 × n 2 2    ∴ n 2 = 2 and 26 . 45 = 52 . 9 × n 2 2    ∴ n 1 = 1 ∵ ΔE = R H hC × z 2 1 n 1 2 - 1 n 2 2 hc λ = R H hC × z 2 1 n 1 2 - 1 n 2 2 6 . 6 × 10 - 34 × 3 × 10 8 λ = 2 . 2 × 10 - 18 × 4 × 1 1 - 1 4 6 . 6 × 10 - 34 × 3 × 10 8 λ = 2 . 2 × 10 - 18 × 4 × 3 4 ∴ λ = 300   A ∴ λ = 30   nm
Related: Chemistry — Structure of Atom · All PYQ Banks