The oxoanion which contains all equivalent M—O bond is :<br>(I) CrO4^2-<br>(II) MnO4^-<br>(III) Cr2O — d and f Block Elements Chemistry Question

💡 Solution & Explanation

Step 1: In the monomeric tetrahedral oxoanions CrO4^2- (chromate) and MnO4^- (permanganate), all metal-oxygen (M-O) bonds are identical in length and strength due to symmetrical resonance delocalization of the negative charges. Step 2: In the dimeric dichromate anion (Cr2O7^2-), there are two different types of Cr-O bonds: six terminal Cr-O bonds (which are shorter due to resonance) and two bridging Cr-O-Cr bonds (which are longer single bonds). Step 3: Therefore, only CrO4^2- and MnO4^- contain completely equivalent M-O bonds, making statements I and II correct, which corresponds to option (c).