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A He-atom is de-excited from and energy level "n" to ground state to emit two consecutive photons of wavelength `1085Å`. Then n will be-A. 3B. 4C. 5D. 6 |
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Answer» Correct Answer - C `E=-13.6 z^(2)//n^(2) =-(13.6xx4)/(n^(2)) =-(54.4)/(n^(2)) eV` in coming to ground state `DeltaE=E_(0) -E_(i)` `=((-54.5)/(n^(2))) -((-54.4)/(1))` `=54.4 (1-(1)/n^(2)) eV` But `DeltaE =E_(pb) =(hc)/(lambda_(1)) +(hc)/(lambda_(2))` `=12400 ((1)/(1085) +(1)/(304)) eV` From (1) & (2) `54.4(1-(1)/(n^(2))) =52.08` `rArr 1-(-1)/(n^(2)) =0.96 rArr n=5` |
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