Question

Vitamin $B_{12}$ contains

• A. Zn (II)
• B. Ca (II)
• C. Fe (II)
• D. Co (III)

Answer 1

The Correct Option is D

Vitamin B₁₂ is an essential water-soluble vitamin that plays a crucial role in the normal functioning of the brain and nervous system, and in the formation of red blood cells. The question asks which metal ion is contained in Vitamin B₁₂.

To solve this, we need to understand the structure of Vitamin B₁₂, which is also known as cobalamin. The name 'cobalamin' itself suggests the presence of cobalt. Indeed, Vitamin B₁₂ contains a cobalt ion, specifically in the +3 oxidation state, which is represented as Co(III).

Let's analyze the given options:

• Zn (II): Zinc is not a component of Vitamin B₁₂.
• Ca (II): Calcium is not a part of Vitamin B₁₂.
• Fe (II): Iron is also not present in Vitamin B₁₂.
• Co (III): This accurately represents cobalt in the +3 oxidation state, which is present in Vitamin B₁₂.

The structure of Vitamin B₁₂ has a central cobalt ion that is coordinated in a corrin ring, which is a complex, cyclic structure. This is what distinguishes Vitamin B₁₂ from other vitamins.

Therefore, the correct answer is:

Co (III)