Question

Which of the following cation will give green colour in Borax bead test

• A. Iron
• B. Cobalt
• C. Manganese
• D. Nickel

Answer 1

The Correct Option is A

The Borax bead test is a qualitative analysis test used for detecting certain metallic cations based on the color they impart to a bead of borax when heated. This test is particularly useful in identifying transition metal ions because of the distinct colors they produce. Let's analyze the options provided for the cation that gives a green color in the borax bead test:

1. Iron (Fe³⁺): In the borax bead test, iron imparts a green color. This happens as iron compounds form iron borates which are characteristically green in color when heated in an oxidizing flame.
2. Cobalt (Co²⁺): Cobalt gives a deep blue color in the borax bead test, not green. This is a distinguishing feature often noted for cobalt compounds.
3. Manganese (Mn²⁺): Manganese typically produces an amethyst (purple) color in the borax bead test due to the formation of manganese oxides.
4. Nickel (Ni²⁺): Nickel generally exhibits a brown color result in the borax bead test.

From the analysis above, we conclude that the cation that gives a green color in the borax bead test is Iron. Therefore, the correct answer is Iron.

Conclusion: The Borax bead test for Iron results in a green-colored bead indicating the presence of iron ions.

Tip: The borax bead test is helpful in identifying transition metals because they form colored compounds due to d-d electronic transitions. Always consider the oxidation state and flame conditions (oxidizing or reducing) as they may affect the result.