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

Options

A. `V^(2+)ltCr^(2+)ltMn^(2+)ltFe^(3+)` 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. `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^(3+)=4` unpaired electrons
Hence, the order of paramagnetic behaviour should be
`V^(2+) lt Cr^(2+)=Fe^(2+) lt Mn^(2+)`(b) Ionic size decreases from left to right in the same period. (c)`Co^(3+)//Co^(2+)=1.97Fe^(3+)//Fe^(2+)=0.77`
`Cr^(3+)//Cu^(2+)=-0.41`
Hence, stability increases as
`Co^(3+) lt Fe^(3+) lt Cr^(3=) lt Sc^(3+)`.
(d) The oxidation states increases as we go from group 3 to group 7 in the same period .