question_answer

The 'brown ring' formed at the junction of two layers in the test of nitrate is due to the formation of a complex ion, \[{{[Fe{{({{H}_{2}}O)}_{5}}NO]}^{2}}.\] Which of the following statements are correct for this complex \[[\mu =3.87B.M.]-\]

(I) Oxidation state of Fe is +1 and NO exists as \[N{{O}^{+}}\]

(II) The complex ion is in octahedral geometry as attained by \[s{{p}^{3}}{{d}^{2}}\]hybridisation

(III) The complex is paramagnetic and has three unpaired electrons due to transfer of electron from NO to \[F{{e}^{2+}}\]

(IV) The complex is octahedral geometry as attained by \[{{d}^{2}}s{{p}^{3}}\] hybridisation

(V) The brown colour of the complex is attributed to d-d-transition of electron

A) I, II and V

B) III, IV and V

C) I, II and III

D) II, III and V

Correct Answer: C

Solution :

\[[\overset{1}{\mathop{Fe}}\,{{({{H}_{2}}O)}_{5}}\overset{+}{\mathop{NO}}\,]\] Number of unpaired electrons  \[=3;\,\,So\,\,\mu =\sqrt{3(2+3)}=3.87\,\,B.M\] Brown colour is due to charge transfer from ligand to metal