Which of the following statement is correct when a mixture of `CaCl_(2) and K_(2)Cr_(2)O_(7)` is gently warmed with conc . `H_(2)SO_(4)` acid ?

Options

A. Deep red vapours are evolved
B. The vapours when passed into NaOH solution gives a yellow solution of `Na_(2)CrO_(4)`
C. Chlorine gas is evolved
D. Chromyl chloride is formed

Answer

To solve the question regarding the reaction of a mixture of CaCl₂ and K₂Cr₂O₇ with concentrated H₂SO₄, we can break down the process step by step.

### Step 1: Identify the Reactants
The reactants in the reaction are:
- Calcium Chloride (CaCl₂)
- Potassium Dichromate (K₂Cr₂O₇)
- Concentrated Sulfuric Acid (H₂SO₄)

### Step 2: Understand the Reaction
When the mixture of CaCl₂ and K₂Cr₂O₇ is gently warmed with concentrated H₂SO₄, a chemical reaction occurs. The main products of this reaction are:
- Chromyl Chloride (CrO₂Cl₂), which is a deep red vapor.
- Potassium Hydrogen Sulfate (KHSO₄)
- Calcium Sulfate (CaSO₄)
- Water (H₂O)

### Step 3: Write the Balanced Chemical Equation
The balanced equation for the reaction can be represented as:
\[ 2 \text{CaCl}_2 + \text{K}_2\text{Cr}_2\text{O}_7 + 4 \text{H}_2\text{SO}_4 \rightarrow 2 \text{CrO}_2\text{Cl}_2 + 2 \text{KHSO}_4 + 2 \text{CaSO}_4 + 4 \text{H}_2\text{O} \]

### Step 4: Analyze the Products
From the balanced equation, we can observe:
- CrO₂Cl₂ is produced, which is known for its deep red color and exists in vapor form.
- The formation of KHSO₄ and CaSO₄ is also noted.

### Step 5: Evaluate the Options
Now, let's evaluate the provided statements:
1. **Deep red vapors are evolved** - This is **correct** because CrO₂Cl₂ is a deep red vapor.
2. **The vapors then pass into NaOH solution. A yellow color solution of Na₂CrO₄ is formed** - This is **correct** because when CrO₂Cl₂ reacts with NaOH, it forms Na₂CrO₄, which is yellow.
3. **Chlorine gas is evolved** - This is **incorrect** because the reaction does not produce chlorine gas; only chromyl chloride vapors are formed.
4. **Chromyl chloride is 4** - This is **correct** as CrO₂Cl₂ is indeed a compound formed in the reaction.

### Conclusion
The correct statements from the options given are:
- Deep red vapors are evolved (A)
- A yellow color solution of Na₂CrO₄ is formed when the vapors pass into NaOH (B)
- Chromyl chloride is 4 (D)

### Final Answer
The correct statements are A, B, and D.

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