The compounds containing complex oxyanion $CrO_4^{2-}$ are intensely yellow coloured because

• A
  Chromium ion in $CrO_4^{2-}$ is a transition metal ion
• B
  $Cr$ and $O$ are $\pi-$ bonded and the allowed $\pi \to \pi^*$ transition occurs in the visible region
• C
  $Cr \to O$ charge transfer is responsible for yellow colour
• D
  Compounds have strong absorption at $\sim 640 \ nm$