question_answer

The complex \[{{[Fe{{({{H}_{2}}O)}_{5}}NO]}^{2+}}\] is formed in the brown ring test for nitrates when freshly prepared \[FeS{{O}_{4}}\] solution is added to aqueous solution of \[NO_{3}^{-}\] followed by addition of conc. \[{{H}_{2}}S{{O}_{4}}\]. Select the correct statement about this complex.

A)  Colour change is due to charge transfer

B)  It has iron in \[+1\] oxidation state and nitrosyl as\[N{{O}^{+}}\]

C)   It has, magnetic moment of \[3.87\,\,BM\] confirming three unpaired electrons in\[Fe\]

D)   All the above are correct statements

Correct Answer: D

Solution :

                \[\left. \begin{align}   & NO\xrightarrow{{}}N{{O}^{+}}+{{e}^{-}} \\  & F{{e}^{2+}}+{{e}^{-}}\xrightarrow{{}}F{{e}^{+}} \\ \end{align} \right]\text{Charge}\,\,\text{transfer}\] \[\therefore \]  Number of unpaired electron,\[n=3\] \[\therefore \]Magnetic moment\[\mu =\sqrt{n(n+2)}\]                                 \[=\sqrt{3(3+2)}\]                                 \[=3.87\,\,BM\] Thus, all the given options are correct.