Question

The number of wavelength in third orbit of h atom

Answer 1

Radius of 3rd orbit = r = R(3)^2

= 9 R

[Here R = Radius of first orbit of hydrogen atom]

mvr = nh / (2 π)

h/(mv) = 2πr / n

λ = h / (mv) = 2π × 9R / 3

λ = 6πR

λ = 6 π × (0.529 Å)

λ = 9.97 Å

De-Broglie wavelength is 9.97 Å

i hope this will help you