Compounds of Cr (II ) are strong reducing

Why Compounds of Cr (II ) are strong reducing- explain ?

Cr(II) state is not very stable.A few compounds which are known get readily oxidised to Cr(III) state in acid solution as well as on exposure to oxygen or air. They are therefore, strong reducing agents.

                  Reaction:   2CrCl₂ + 2 HCl  ⟶ 2 CrCl_3十H₂

        
Exception: 

Some of  the hydrated salts of Cr(II) are more stable.

For example: 

CrCl₂.H₂O and CrSO₄.7H₂O .

Besides these, Cr (II) acetate hydrate is known to exist  as a dimer [(CH₃COO)₂Cr.H₂O]₂  

Metal chromium

                  _{[Ar] 3d5 4s1
                       electronic configuration of chromium in ground state.}