The incorrect statement in respect of chromyl chloride test is

Options

A. formation of red vapour
B. formation of lead chromate
C. formation of chromyl chloride
D. liberation of chlorine

Explanation

To solve the question about the incorrect statement regarding the chromyl chloride test, we can break it down into several steps:

### Step-by-Step Solution:

1. **Understanding the Chromyl Chloride Test**:
- The chromyl chloride test is primarily used to detect the presence of chloride ions in a sample. It involves the reaction of a chloride salt with potassium dichromate (K2Cr2O7) and sulfuric acid (H2SO4).

2. **Reaction Formation**:
- When a chloride salt is mixed with potassium dichromate and sulfuric acid, chromyl chloride (CrO2Cl2) is formed along with potassium hydrogen sulfate (KHSO4). The reaction can be represented as:
\[ \text{Cl}^- + K_2Cr_2O_7 + H_2SO_4 \rightarrow CrO_2Cl_2 + KHSO_4 \]

3. **Observation of Red Fumes**:
- The chromyl chloride produced gives off red fumes, which is a characteristic observation of this test.

4. **Further Reaction with NaOH**:
- The red fumes of chromyl chloride can be reacted with sodium hydroxide (NaOH), resulting in the formation of sodium chromate (Na2CrO4), which is yellow in color:
\[ CrO_2Cl_2 + 2NaOH \rightarrow Na_2CrO_4 + NaCl + H_2O \]

5. **Formation of Lead Chromate**:
- If lead acetate (Pb(C2H3O2)2) is added to the yellow sodium chromate solution, lead chromate (PbCrO4), which is yellow, will precipitate:
\[ Na_2CrO_4 + Pb(C_2H_3O_2)_2 \rightarrow PbCrO_4 + 2NaC_2H_3O_2 \]

6. **Identifying the Incorrect Statement**:
- The question asks for the incorrect statement regarding the chromyl chloride test. The key point is that during this test, chlorine gas (Cl2) is **not** liberated at any stage. Therefore, any statement claiming the liberation of chlorine gas is incorrect.

### Conclusion:
The incorrect statement in respect of the chromyl chloride test is the **liberation of chlorine gas** (Cl2).

---