Question

In the dichromate dianion, the Cr-O-Cr bond angle is ______.

Options

• 90°

• 120°

• 126°

• 131°

Answer 1

In the dichromate dianion, the Cr-O-Cr bond angle is 126°.

Explanation:

In the dichromate ion Cr2O7²⁻, two CrO₄ tetrahedra share one oxygen atom (a bridging oxygen). The angle formed at this bridging oxygen between the two chromium atoms is called the Cr-O-Cr bond angle. Due to tetrahedral geometry and repulsion between lone pairs and bonding pairs, this angle is approximately 126°.