Which of the following increasing order of oxidising power is correct for the following species?
`VO_(2)^(+),MnO_(4)^(-),Cr_(2)O_(7)^(2-)`

Options

A. `VO_(2^(+)) lt Cr_(2)O_(7^(2))`
B. `VO_(2^(+)) lt MnO_(4) lt Cr_(2)O_(7)^(2-)`
C. `Cr_(2)O_(7^(2)) lt MnO_(4)`
D. `Cr_(2)O_(7^(2-)) lt MnO_(4^(-)) lt VO_(2^(+))`.

Answer

A

Explanation

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 valence shell electron configuration `[3d^(5)].Cr_(2)O_(7)^(2-)` is reduced to` Cr^(3+)` which has half filled `t_(2g)^(3)` energy level of 3d orbitals in octahedral crystal field spliting.
`VO_(2^(+))` is reduced to `V^(3+)` which has electronic configuration `[Ar]^(18)3d^(2)4s^(0)`
so the order of increasing stability of the reduced species is `Mn^(2+) gt Cr^(3+) gt V^(3+)` and, therefore, the increasing order of oxidising power is `VO_(2^(+)) lt Cr_(2)O_(7^(2-)) lt MnO_(4^(-))`.