NEET Sample Paper NEET Sample Test Paper-19

  • question_answer Which energy state of doubly ionized lithium \[(L{{i}^{++}})\]has the same energy as that of the ground state of hydrogen? Given Z for lithium = 3.

    A) \[~n=1\]                      

    B) \[~n=2\]

    C) \[~n=3\]                    

    D) \[~n=4\]

    Correct Answer: C

    Solution :

    \[{{E}_{n}}=\frac{c{{z}^{2}}}{{{n}^{2}}}.\] For \[n=1\]state of hydrogen, we have \[{{E}_{1}}=c\]and for the nth state of \[L{{i}^{++}},\]we have \[{{E}_{n}}=\frac{c{{.3}^{2}}}{{{n}^{2}}}=\frac{9c}{{{n}^{2}}}\]             For \[{{E}_{1}}={{E}_{n}}\]we require Hence, the correction option is [c]. \[C=\frac{9C}{{{n}^{2}}}\]which gives \[n=3.\]Hence \[n=3.\]


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