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NEET AIPMT SOLVED PAPER MAINS 2012

  • question_answer
     (\[{{\Delta }_{o}}=\] crystal field splitting energy in an octahedral field, P = electron pairing energy) Which one of the following does not correctly represent the correct order of the property indicated against it?

    A) \[Ti<V<Cr<Mn\]: increasing number of oxidation states

    B)  \[T{{i}^{3+}}<{{V}^{3+}}<C{{r}^{3+}}<M{{n}^{3+}}\]: increasing magnetic moment

    C)  \[Ti<V<Cr<Mn\]: increasing melting points

    D)  \[Ti<V<Mn<Cr\]: increasing second ionisation enthalpy

    Correct Answer: C

    Solution :

    (a)
    Element Oxidation states
    \[Ti\] \[+2,+3,+4\]
    \[V\] \[+2,+3,+4,+5\]
    \[Cr\] \[+1,+2,+3,+4,+5,+6\]
    \[Mn\] \[+1,+2,+3,+4,+5,+6,+7\]
    \[\therefore \] Order of oxidation states is \[Ti<V<Cr<Mn\] (b) \[\because \] Magnetic moment, \[\mu =\sqrt{n(n+2)}\] where, n =no. of unpaired electrons                
    Ion Outermost electronic arrangement No. of unpaired electron
    \[T{{i}^{3+}}\] \[{{V}^{3+}}\] \[C{{r}^{3+}}\] \[M{{n}^{3+}}\] \[3{{d}^{1}}\] \[3{{d}^{2}}\] \[3{{d}^{3}}\] \[3{{d}^{4}}\] \[1\] 2 3 4
    \[\therefore \] Order of magnetic moment is \[T{{i}^{3+}}<{{V}^{3+}}<C{{r}^{3+}}<M{{n}^{3+}}\]


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