question_answer

Which of the following processes does not involve oxidation of iron?                         [NEET 2015]

A)  Rusting of iron sheets

B)  Decolourisation of blue \[CuS{{O}_{4}}\] solution by iron

C)  Formation of \[Fe{{(CO)}_{5}}\] from Fe

D)  Liberation of Hg from steam by iron a high temperature Correct Answer: C Solution : [a] \[\overset{0}{\mathop{Fe}}\,+\underbrace{{{H}_{2}}O+{{O}_{2}}}_{\text{from}\,\,\text{air}}\xrightarrow{\,}\overset{\text{III}}{\mathop{F{{e}_{2}}}}\,{{O}_{3}}.x{{H}_{2}}O]\]

[b] \[\overset{0}{\mathop{Fe}}\,+CuS{{O}_{4}}\xrightarrow{\,}\overset{\text{III}}{\mathop{Fe}}\,S{{O}_{4}}+Cu\]

[c] \[\overset{0}{\mathop{Fe}}\,+5CO\xrightarrow{\,}\overset{0}{\mathop{Fe}}\,{{\left( CO \right)}_{5}}\]

[d] \[\overset{0}{\mathop{Fe}}\,+\underset{Steam}{\mathop{{{H}_{2}}O}}\,\xrightarrow{\,}\overset{III}{\mathop{Fe}}\,{{O}_{3}}+{{H}_{2}}\]

\[\therefore \] Formation of \[Fe{{\left( CO \right)}_{5}}\] from Fe does not involve oxidation of iron because there is no change in oxidation state.