Question

The incorrect statement is:

Options

• the colour of [CoCl(NH₃)₅]²⁺ is violet as it absorbs the yellow light.

• the gemstone, ruby, has Cr³⁺ ions occupying the octahedral sites of beryl.

• the spin-only magnetic moment of [Ni(NH₃)₄(H₂O)₂]²⁺ is 2.83 BM.

• the spin-only magnetic moments of [Fe(H₂O)₆]²⁺ and [Cr(H₂O)₆]²⁺ are nearly similar.

Answer 1

The gemstone, ruby, has Cr³⁺ ions occupying the octahedral sites of beryl.

Explanation:

• Ruby is a gemstone composed of aluminum oxide (Al₂O₃), with trace amounts of Cr³⁺ ions. However, in ruby, the Cr³⁺ ions are located in the octahedral sites of the corundum crystal structure, not beryl. Beryl is a different mineral with a hexagonal crystal structure that forms gemstones like emerald (with Cr³⁺) and aquamarine.
• Beryl and ruby are two different minerals, so it’s incorrect to state that ruby contains Cr³⁺ ions in the octahedral sites of beryl.

Thus, the statement about ruby and beryl is incorrect because ruby contains Cr³⁺ in its own octahedral sites (in corundum), not in the beryl structure.