If the radius of first orbit of H - atom is a0, then de Broglie wavelength of electron in 4th orbit is ?
2πa0
16a0
a04
8πa0
rn=a0×n2,r4=a0×42=16a0mv=4.h2πr4=4h2π×16a0=h8πa0λ=hmv=8πa0