Which of the following is incorrect about `K_(2)Cr_(2)O_(7)` ?

Options

A. It can be prepared from `K_(2)CrO_(4)`.
B. It is used in redox titrations.
C. It is stable in both acid & base.
D. It is orange in colour

Explanation

To determine which statement about potassium dichromate (K₂Cr₂O₇) is incorrect, we will analyze each option provided.

### Step 1: Analyze Option A
**Statement:** It can be prepared from K₂CrO₄ (potassium chromate).

**Analysis:** This statement is correct. Potassium dichromate can indeed be prepared from potassium chromate by reacting it with sulfuric acid (H₂SO₄). The reaction is as follows:
\[ \text{K}_2\text{CrO}_4 + \text{H}_2\text{SO}_4 \rightarrow \text{K}_2\text{Cr}_2\text{O}_7 + \text{K}_2\text{SO}_4 + \text{H}_2\text{O} \]
Thus, Option A is correct.

### Step 2: Analyze Option B
**Statement:** It is used in redox titration.

**Analysis:** This statement is also correct. Potassium dichromate is commonly used as a powerful oxidizing agent in redox titrations, particularly in acidic medium. For example, it can oxidize ferrous ions (Fe²⁺) to ferric ions (Fe³⁺) while itself being reduced. Therefore, Option B is correct.

### Step 3: Analyze Option C
**Statement:** It is stable in both acid and base.

**Analysis:** This statement is incorrect. The dichromate ion (\( \text{Cr}_2\text{O}_7^{2-} \)) is stable in acidic conditions. However, in basic conditions, it converts to the chromate ion (\( \text{CrO}_4^{2-} \)). Therefore, it is not stable in both acidic and basic media. Thus, Option C is incorrect.

### Step 4: Analyze Option D
**Statement:** It is orange in color.

**Analysis:** This statement is correct. Potassium dichromate is known for its distinctive orange color. Therefore, Option D is correct.

### Conclusion
The incorrect statement about potassium dichromate (K₂Cr₂O₇) is **Option C**: "It is stable in both acid and base."

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