Direction for: In each of the following questions a statement of Assertion is given followed by a corresponding statement of Reason just below it. Of the statements mark the correct answer as
Assertion In the Lyman series of H-spectra, the maximum wavelength of lines is 121.65 nm. Reason Wavelength is maximum if there is transition from the very next level.A) If both Assertion and Reason are true and Reason is the correct explanation of Assertion.
B) If both Assertion and Reason are true but Reason is not the correct explanation of Assertion.
C) If Assertion is true but Reason is false.
D) If both Assertion and Reason are false.
Correct Answer: D
Solution :
\[\frac{1}{\lambda }={{R}_{H}}{{Z}^{2}}\left[ \frac{1}{n_{1}^{2}}-\frac{1}{n_{2}^{2}} \right]\] For Lyman series, \[{{n}_{1}}=1\]and \[{{n}_{2}}=2\] [\[\because \] for maximum \[\lambda ,\] transition is from very next level.] \[\therefore \] \[\frac{1}{\lambda }=109678\times {{(1)}^{2}}\left[ \frac{1}{{{(1)}^{2}}}-\frac{1}{{{(2)}^{2}}} \right]c{{m}^{-1}}\] or \[=\frac{109678\times 3}{4}c{{m}^{-1}}\] \[\lambda =\frac{4\times {{10}^{7}}\times {{10}^{-7}}}{3\times 109678}\,cm=121.65\,nm.\]
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