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

Options

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

Answer

A

Explanation

(a) `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+) lt Fe^(2+) lt Mn^(2+)`
(b) ionic size decrease from left to right in same period.
(c) `Co^(3+) //Co^(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.