Question

Which of the following increasing order of oxidising power is correct for the following species?
`VO_(2)^(+),MnO_(4)^(-),Cr_(2)O_(7)^(2-)`
A. `VO_(2)^(+)ltCr_(2)O_(7)^(2-)lt MnO_(4)^(-)`
B. `VO_(2)^(+)ltMnO_(4)^(-)ltCr_(2)O_(7)^(2-)`
C. `Cr_(2)O_(7)^(2-) lt VO_(2)^(+)ltMnO_(4)^(-)`
D. `Cr_(2)O_(7)^(2-)ltMnO_(4)^(-)ltVO_(2)^(+)`

Answer 1

This is attributed to the increasing stability of the lower species to which they are reduced. `MnO_(4)^(-)` is reduced to `Mn^(2+)` which has stable half filled valency shell electron configuration `[3d^(5)]` `Cr_(2)O_(7)^(2-)`is reduced to `Cr_(3+)` which has half filled `t^(3)_(2g)` energy levels of `3d` orbitals in octahedral crystal field spliting `VO_(2)^(+)` is reduced to `V^(3+)` which has electonioc configuration `[Ar]^(18)3d^(2)4S^(0)`. So the order of increasing stability of the reduced species is `mn^(2+)gtCr^(3+)gtV^(3+)` and , therefore, the increasing order of oxidising power is `VO_(2)^(+)ltCr_(2)O_(7)^(2-)ltMnO_(4)^(-)` .
Therefor, (a) option is correct.