The correct statements about $$\mathrm{Mn_2O_7}$$ are:

(A) Mn is tetrahedrally surrounded by oxygen atoms.

(C) Contains Mn-O-Mn bridge.

Manganese (Mn) in $$\mathrm{Mn_2O_7}$$ exhibits its highest oxidation state of +7. The oxidation state is the charge an atom would have if the electrons in a chemical bond were shared equally.

In $$\mathrm{Mn_2O_7}$$, the manganese atoms are surrounded by oxygen atoms in a tetrahedral arrangement. This means that each manganese atom is bonded to four oxygen atoms arranged in a pyramid shape. This tetrahedral arrangement of oxygen atoms results in the highest oxidation state for manganese in $$\mathrm{Mn_2O_7}$$.

$$\mathrm{Mn_2O_7}$$ also contains Mn-O-Mn bridges, which are bonds between two manganese atoms through a shared oxygen atom. These bonds help to reinforce the structure of the molecule and contribute to its stability.

It is incorrect to state that Mn is octahedrally surrounded by oxygen atoms or that $$\mathrm{Mn_2O_7}$$ contains a Mn-Mn bond. An octahedral arrangement would consist of six oxygen atoms surrounding a central manganese atom, and a Mn-Mn bond would involve two manganese atoms sharing electrons without an oxygen atom in between. Neither of these are present in $$\mathrm{Mn_2O_7}$$.