Orange coloured sodium cobaltinitrite `Na_(3)[Co(NO_(3))_(6)]` is used for the detection of `K^(Theta)` which gives …… ppt due to the formation of pot sod cobaltinitrite `K_(2)Na[Co(NO_(2))_(6)]`

Options

A. White
B. Orange
C. Yellow
D. Brown

Answer

To solve the question regarding the detection of potassium ion (K⁺) using sodium cobaltinitrite (Na₃[Co(NO₂)₆]), we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Reactants**:
- The reactant mentioned is sodium cobaltinitrite, which has the formula Na₃[Co(NO₂)₆]. This compound is orange in color.

2. **Understand the Reaction**:
- When potassium ions (K⁺) are present, they react with sodium cobaltinitrite. In this reaction, the potassium ions replace the sodium ions in the cobaltinitrite complex.

3. **Write the Reaction**:
- The reaction can be represented as:
\[ 3 K^+ + Na_3[Co(NO_2)_6] \rightarrow K_2Na[Co(NO_2)_6] + 2 Na^+ \]
- Here, potassium ions replace two sodium ions, forming potassium sodium cobaltinitrite.

4. **Determine the Color of the Precipitate**:
- The product formed, potassium sodium cobaltinitrite (K₂Na[Co(NO₂)₆]), is known to produce a yellow precipitate.

5. **Conclusion**:
- Therefore, the color of the precipitate formed when potassium ions react with sodium cobaltinitrite is yellow.

### Final Answer:
The color of the precipitate is **yellow**.