Atoms And Nuclei Question 311

Question: The ionization energy of a hydrogen like Bohr atom is 4 Rydbergs. Find the wavelength of the radiation emitted when the electron jumps from the first excited state to the ground state

Options:

A) $ 300A{}^\circ $

B) $ 2.5\times {{10}^{-11}}m $

C) $ 100A{}^\circ $

D) $ 1.5\times {{10}^{-11}}m $

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Answer:

Correct Answer: A

Solution:

  • $ E _{n}=-\frac{I.E.}{n^{2}} $ for Bohr “s hydrogen atom. Here, $ I.E/=4R\text{ }\therefore E _{n}=\frac{-4R}{n^{2}} $

    $ \therefore E _{2}-E _{1}=\frac{-4R}{2^{2}}-( -\frac{4R}{l^{2}} )=3R $ ..(i) $ E _{2}-E _{1}=hv=\frac{hc}{\lambda } $ .(ii) From (i) and (ii)

    $ \therefore \lambda =\frac{hc}{3R}=\frac{6.6\times {{10}^{-34}}\times 3\times 10^{8}}{2.2\times {{10}^{-18}}\times 3}=300\overset{o}{\mathop{A}}, $



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