Q.

If an electron in a hydrogen atom jumps from the 3rd orbit to the 2nd orbit, it emits a photon of wavelength λ. When it jumps from the 4th orbit to the 3rd orbit, the corresponding wavelength of the photon will be           [2016]

1 1625λ  
2 916λ  
3 207λ  
4 2013λ  

Ans.

(3)

When electron jumps from higher orbit to lower orbit, then the wavelength of emitted photon is given by,

      1λ=R(1nf2-1ni2)

so,  1λ=R(122-132)=5R36  and  1λ'=R(132-142)=7R144

   λ'=1447×5λ36=20λ7