The first transition series metal ' $M$ ' has the highest enthalpy of atomisation in its series. One of its aquated ion $\left(\mathrm{M}^{\mathrm{n}+}\right)$ exists in green colour. The nature of the oxide formed by the above $\mathrm{M}^{\mathrm{n}+}$ ion is:

Pair of transition metal ions having the same number of unpaired electrons is

Given below are two statements:

Statement I : $\mathrm{CrO}_3$ is a stronger oxidizing agent than $\mathrm{MoO}_3$

Statement II : $\mathrm{Cr}(\mathrm{VI})$ is more stable than $\mathrm{Mo}(\mathrm{VI})$

In the light of the above statements, choose the correct answer from the options given below

The metal ions that have the calculated spin-only magnetic moment value of 4.9 B.M. are :

A. $\mathrm{Cr}^{2+}$

B. $\mathrm{Fe}^{2+}$

C. $\mathrm{Fe}^{3+}$

D. $\mathrm{Co}^{2+}$

E. $\mathrm{Mn}^{3+}$

Choose the correct answer from the options given below: