JEE Main & Advanced Sample Paper JEE Main - Mock Test - 27

  • question_answer
    Which of the following complexes is/are coloured?
    (I). \[[Ti{{(N{{O}_{3}})}_{4}}]\]               
    (II) \[{{[Cu(NC-C{{H}_{3}})]}^{\oplus }}Cl{{O}_{4}}^{\Theta }\]
    (III) \[{{[Cr{{(N{{H}_{3}})}_{6}}]}^{3+}}3B{{F}_{4}}^{\Theta }\]
    (IV) \[N{{a}_{3}}[V{{F}_{6}}]\]

    A) I, II                  

    B)        III, IV                

    C) II, III, IV             

    D)        All

    Correct Answer: B

    Solution :

    [b] (I) \[[Ti{{(N{{O}_{3}})}_{4}}]\]
    \[Ti=[Ar]\,\,3{{d}^{2}}\,\,4{{s}^{2}}\]
    \[T{{i}^{4+}}=[Ar]\,\,3{{d}^{0}}\]
    No unpaired electron. So it is colourless.
    (II)   \[{{[Cu(NCC{{H}_{3}})]}^{\oplus }}\]
    \[Cu=[Ar]\,\,3{{d}^{10}}4{{s}^{1}}\]
    \[+1\]
    \[Cu=[Ar]3{{d}^{10}}\]
    No unpaired electrons. So it is colourless.
    (III)  \[{{[Cr{{(N{{H}_{3}})}_{6}}]}^{3+}}\]
    \[Cr=[Ar]\,\,3{{d}^{5}}4{{s}^{1}}\]
    \[+3\]
    \[Cr=[Ar]\,3{{d}^{3}}\]
    It has 3 unpaired electrons. So it is coloured.
    (IV) \[N{{a}_{3}}[V{{F}_{6}}]\]
    \[V=[Ar]\,3{{d}^{3}}4{{s}^{2}}\]
    \[{{V}^{3+}}=[Ar]\,3{{d}^{2}}\]
    It has 2 unpaired electron. So it is coloured.


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