Transition and InnerTransition Elements - Result Question 97

####24. Which of the following arrangements does not represent the correct order of the property stated against it? (2013 Main)

(a) V2+<Cr2+<Mn2+<Fe2+ : paramagnetic behaviour

(b) Ni2+<Co2+<Fe2+<Mn2+ : ionic size

(c) Co3+<Fe3+<Cr3+<Sc3+ : stability in aqueous solution

(d) Sc<Ti<Cr<Mn : number of oxidation states

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Solution:

  1. (a) V2+=3 unpaired electrons

Cr2+=4 unpaired electrons

Mn2+=5 unpaired electrons

Fe2+=4 unpaired electrons

Hence, the order of paramagnetic behaviour should be

V2+<Cr2+<Fe2+<Mn2+

(b) Ionic size decreases from left to right in the same period.

(c) (As per data from NCERT)

Co3+/Co2+=1.97; Fe3+/Fe2+=0.77; Cr3+/Cr2+=0.41

Sc3+ is highly stable (It does not show +2 ).

(d) The oxidation states increases as we go from group 3 to group 7 in the same period.



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