(1)

V = 3d34s2	V2+ = 3d3	= 3 unpaired electron
Cr = 3d54s1	Cr2+ = 3d4	= 4 unpaired electron
Mn = 3d54s2	Mn2+ = 3d5	= 5 unpaired electron
Fe = 3d64s2	Fe2+ = 3d6	= 4 unpaired electron

hence the correct order of paramagnetic behaviour

$${V^{2 + }} < Cr{}^{2 + } = F{e^{2 + }} < M{n^{2 + }}$$

(2) $$\,\,\,\,$$

For the same oxidation state, the-ionic radii generally $$dc$$-creases as the atomic number increases in a particular transition series.

Hence the order is

$$M{n^{ + + }} > F{e^{ + + }} > C{o^{ + + }} > N{i^{ + + }}$$

(3)

In solution, the stability of the compounds depends upon electrode potentials, $$SEP$$ of the transitions metal ions are given as

$$C{o^{3 + }}/Co = + 1.97,\,\,\,F{e^{3 + }}/Fe = + 0.77;$$

$$C{r^{3 + }}/C{r^{2 + }} = - 0.41,\,\,S{c^{3 + }}$$ is highly stable as it does not show $$+2$$ $$O.$$ $$S.$$

(4)

$$Sc - \left( { + 2} \right),\left( { + 3} \right)$$

$$Ti - \left( { + 2} \right),\left( { + 3} \right),\left( { + 4} \right)$$

$$Cr - \left( { + 1} \right),\left( { + 2} \right),\left( { + 3} \right),\left( { + 4} \right),\left( { + 5} \right),\left( { + 6} \right)$$

$$Mn - \left( { + 2} \right),\left( { + 3} \right),\left( { + 4} \right),\left( { + 5} \right),\left( { + 6} \right),\left( { + 7} \right)$$

$$i.e.\,Sc < Ti < Cr = Mn$$

$${E_a} = 53598.6J/mol$$

$$ = 53.6\,kJ/mol.$$