Discussion Forum



1)

The correct statement (s) about Cr2+  and Mn3+  is/are  [atomic  number of Cr=24 and Mn=25]


A) $ Cr^{2+}$ is a reducing agent

B) $Mn^{3+}$ is an oxidising agent

C) both $Cr^{2+}$ and $Mn^{3+}$ exhibit $d^{4}$ electronic configuration

D) when $Cr^{2+}$ is used as a reducing agent, the chromium ion attains $d^{5}$ electronic configuration

Answer:

Option A,B,C

Explanation:

(a) In an aqueous solution  Cr2+ (3d4)  acts as a reducing agent, oxidising itself to  Cr3+ (3d3)  that gives a completely half-field t2g level in the octahedral ligand field of H2O.

(b)   Mn3+ (3d4) is an oxidising agent as it is reduced to Mn2+  (3d5) , a completely half-filled stable configuration.

(c) Both Cr2+  and Mn3+ have d4  configuration.

(d) $3d^{4}Cr^{2+}(aq)$         $\underrightarrow{R.A}$       $Cr^{3+}(aq)+\overline{e}$

 hence (d) is wrong statement.