Amongst the following, identify the species with an atom in +6 oxidation state. [MnO4]−, [Cr(CN)6]3−, Cr2O3, CrO2Cl2

Let x be the oxidation state of the element whose oxidation no. we want to find for a compound.
Oxidation no. of Manganese (Mn) in MnO₄⁻ is: x + 4(-2) = -1; x = 7
Oxidation no. of Chromium (Cr) in [Cr(CN)6]³⁻ is: x + 6(-1) = -3; x = 3
Oxidation no. of Chromium (Cr) in Cr₂O₃ is: 2x + 3(-2) = 0; x = 3
Oxidation no. of Chromium (Cr) in CrO₂Cl₂ is: x + 2(-2) + 2(-1) = 0; x = 6
Hence, option D is correct.