Consider following reaction:
`Cl_(2)(g)+H_(2)O overset(R.T.)to P+Q`
If molecular weight of P is less than Q then incorrect statement is:

Options

A. On warming 'P' can form deep red coloured vapours with `CrO_(3)`
B. Q' exhibits bleaching property
C. `MnO_2` can change 'P' into `Cl_(2)` gas on warming
D. P' reacts with `H_(2)S` gas while 'Q' does not

Explanation

To solve the given question, we need to analyze the reaction between chlorine gas (Cl₂) and water (H₂O) at room temperature, which produces two products, P and Q. We are also given that the molecular weight of P is less than that of Q. Let's break down the solution step by step.

### Step 1: Identify the Reaction
The reaction is:
\[ \text{Cl}_2(g) + \text{H}_2\text{O} \rightarrow P + Q \]

### Step 2: Determine the Products
When chlorine gas reacts with water, the products formed are hydrochloric acid (HCl) and hypochlorous acid (HOCl):
\[ \text{Cl}_2 + \text{H}_2\text{O} \rightarrow \text{HCl} + \text{HOCl} \]

### Step 3: Assign P and Q
According to the problem, we need to assign P and Q based on the molecular weights:
- Let P = HCl (molecular weight = 36.46 g/mol)
- Let Q = HOCl (molecular weight = 52.46 g/mol)

Since the molecular weight of P (HCl) is less than that of Q (HOCl), this assignment is consistent with the given information.

### Step 4: Analyze the Statements
Now we need to evaluate the statements provided in the question to find the incorrect one.

1. **Statement A**: "On warming, P can form deep red colored vapors with CrO₃."
- **Analysis**: HCl does not form deep red vapors with CrO₃; this statement is incorrect.

2. **Statement B**: "Q exhibits bleaching property."
- **Analysis**: HOCl is known to have bleaching properties. This statement is correct.

3. **Statement C**: "MnO₂ can change P into Cl₂ gas on burning."
- **Analysis**: HCl can react with MnO₂ to produce Cl₂ gas. This statement is correct.

4. **Statement D**: "P reacts with H₂S gas while Q does not."
- **Analysis**: HCl does not react with H₂S, while HOCl can react with H₂S. This statement is incorrect.

### Step 5: Conclusion
Based on the analysis, the incorrect statement is:
- **Statement A**: "On warming, P can form deep red colored vapors with CrO₃."

Thus, the answer is **A**.