Haryana PMT Haryana PMT Solved Paper-2011

  • question_answer
    The Rydberg constant for hydrogen is 10967700/m. The shortest and longest   wavelength limit in its Lyman series will be   respectively

    A) \[911\overset{\text{o}}{\mathop{\text{A}}}\,,\text{ }1215\overset{\text{o}}{\mathop{\text{A}}}\,\]

    B) \[1011\overset{\text{o}}{\mathop{\text{A}}}\,,\text{ }1515\overset{\text{o}}{\mathop{\text{A}}}\,\]

    C) \[711\overset{\text{o}}{\mathop{\text{A}}}\,,\text{ }575\overset{\text{o}}{\mathop{\text{A}}}\,\]

    D) None of these

    Correct Answer: A

    Solution :

                    For Lyman series                 \[\frac{1}{\pi }=R\left[ \frac{1}{{{\left( 1 \right)}^{2}}}-\frac{1}{{{n}^{2}}} \right]\]Where, n = 2,3,4,5,?                 \[\frac{1}{{{\lambda }_{shortest}}}=R\left[ \frac{1}{{{\left( 1 \right)}^{2}}}-\frac{1}{\infty } \right]=10967700/s\]                 \[\frac{1}{{{\lambda }_{shortest}}}=R\frac{1}{10967700}=911\overset{0}{\mathop{\text{A}}}\,\]                 Longest wavelength limit                 \[\frac{1}{{{\lambda }_{shortest}}}=R\left[ \frac{1}{{{1}^{2}}}-\frac{1}{{{2}^{2}}} \right]=\frac{3}{4}R\]                 \[{{\lambda }_{longets}}=\frac{4}{3R}\]                 \[=\frac{4}{3\times 10967700}=1215\overset{0}{\mathop{\text{A}}}\,\]


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