A. Mn forms the oxide $\mathrm{Mn_2O_7}$, in which Mn is in its highest oxidation state.

B. Oxygen stabilizes the Mn in higher oxidation states by forming multiple bonds with Mn.

C. $\mathrm{Mn_2O_7}$ is an ionic oxide.

D. The structure of $\mathrm{Mn_2O_7}$ consists of one bridged oxygen.

Choose the correct answer from the options given below :

$\mathrm{MnO}_4{ }^{2-}$, in acidic medium, disproportionates to :

The correct decreasing order of spin only magnetic moment values (BM) of Cu⁺, Cu²⁺, Cr²⁺ and Cr³⁺ ions is :

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: