Question

If the radius of the first Bohr orbit is x, then de Broglie wavelength
of electron in 3rd orbit is nearly
1) 3x
2)6 pi x
3) 2 pi x
4) 9x​

Answer 1

According to de-Broglie's formula for orbit wavelength,

nλ = 2 pi r(n)

λ(3rd orbit) = 2 pi (3x)

λ = 6 pi x.