Which of the following arrangements does not represent the correct order of the property stated against it?

Options

A. `V^(2+)lt Cr^(2+)ltMn^(2+)ltFe^(2+)`: paramagnetic behaviour
B. `Ni^(2+)ltCo^(2+)ltFe^(2+)ltMn^(2+)`: ionic size
C. `Co^(3+)ltFe^(3+)ltCr^(3+)ltSc^(3+):` stability in aqueous solution
D. `Si lt Ti lt Cr lt Mn:` number of oxidation states

Answer

A

Explanation

`V^(2+)=3` unpaired electrons
`Cr^(2+)=4` unpaired electrons
`Mn^(2+)=5` unpaired electrons
`Fe^(2+)=4` unpaired electrons
Hence the order of paramagnetic behaviour should be
`V^(2+)lt Cr^(2+)ltFe^(2+)lt Mn^(2+)`
(b) ionic size decrease from left to right in same peirod.
(c) `Co^(3+)//Cr^(2+)=1.97, Fe^(3+)//Fe^(2+)=0.77`,
`Cr^(3+)//Cr^(2+)=-0.41`
`Sc^(3+)` is highly stable (It does not show `+2` oxidation state.)
(d) The oxidation states increases as we go from group 3 to group 7 in same period.