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NEET - 2012

Electron in hydrogen atom first jumps from third exicted state to second exicted state and then from second exicted to the first excited state. The ratio of the wavelengths λ1:λ2 emitted in the two cases is

(a) 7/5

(b) 27/20

(c) 27/5

(d) 20/7

Here, for wavelength λ1

n1=4 and n2=3

and for λ2, n1=3 and n2=2 

We have hcλ=-13.61n22-1n12

So, for λ1

       hcλ1=-13.6142-132

         hcλ1=13.67144                                ...(i)

Similarly, for λ2

       hcλ1=-13.6132-122

         hcλ1=-13.6536                    ...(ii)

Hence, from Eqs. (i) and (ii), we get 

                     λ1λ2=207

Difficulty Level:

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