Question

For the dichromate dianion, which of the following is true?
1) $4Cr-O$ bonds are equivalent
2) $6Cr-O$ bonds are equivalent

Answer 1

The correct answer is - There are '6' identical $Cr-O$ bonds in the dichromate ion$\left(C{r}_2{O}_2^{2-}\right).$

In a dichromate ion $\left(C{r}_2{O}_7^{2-}\right).$, there are 6 terminal $Cr–O$ bonds. All these bonds are equivalent due to resonance.

The Dichromate ions $\left(C{r}_2{O}_7^{2-}\right).$ are oxoanions of chromium in the oxidation state +6.