Which of the following tests cann you identify `K^(+)` in a salt?

Options

A. Flame test (violet) and precipitation (yellow) with sodium cobaltinitrite
B. Flame test (violet) and precipitation (violet) with sodium cobaltinitrite
C. Flame test (crimson) and precipitation (yellow) with sodium cobaltinitrite
D. Flame test (golden) and precipitation (violet) with sodium cobaltinitrite

Answer

To identify the presence of \( K^+ \) (potassium ion) in a salt, we can perform a couple of tests. Here’s a step-by-step solution:

### Step 1: Flame Test
1. **Procedure**: Take a small amount of the salt containing \( K^+ \) and place it in a flame (preferably a clean Bunsen burner flame).
2. **Observation**: Observe the color of the flame.
3. **Result**: If the flame turns violet, it indicates the presence of \( K^+ \) ions.

### Step 2: Sodium Cobalt Nitrate Test
1. **Procedure**: Dissolve the salt in water and add sodium cobalt nitrate solution (\( Na_3[Co(NO_2)_6] \)).
2. **Observation**: Look for the formation of a precipitate.
3. **Result**: If a yellow precipitate forms, it confirms the presence of \( K^+ \) ions.

### Conclusion
Based on the tests:
- The flame test shows a violet flame for \( K^+ \).
- The sodium cobalt nitrate test produces a yellow precipitate.

Thus, the presence of \( K^+ \) can be confirmed by these tests.

### Final Answer
The tests that can identify \( K^+ \) in a salt are:
1. Flame test (producing a violet flame).
2. Sodium cobalt nitrate test (producing a yellow precipitate).