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

Options

A. Deep red vapours are liberated
B. Deep red vapours dissolved in `NaOH(aq)` forming a yellow solution.
C. Greenish yellow gas is liberated
D. Deep red vapour dissolve in water forming yellow solution.

Explanation

To solve the question regarding the mixture of NaCl and K2Cr2O7 when gently warmed with concentrated H2SO4, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Reaction**:
- When NaCl and K2Cr2O7 are mixed and gently warmed with concentrated H2SO4, a chemical reaction occurs. The concentrated sulfuric acid acts as a dehydrating agent and facilitates the formation of chromyl chloride (CrO2Cl2) and chlorine gas (Cl2).

2. **Identifying Products**:
- The main products of the reaction are:
- Chromyl chloride (CrO2Cl2), which is responsible for the deep reddish vapor observed.
- Chlorine gas (Cl2).
- Other byproducts such as potassium hydrogen sulfate (KHSO4) and sodium hydrogen sulfate (NaHSO4) may also form.

3. **Observing the Color of Vapors**:
- The deep red vapors that are liberated during the reaction are indicative of the presence of chromyl chloride. This confirms that the first statement regarding the liberation of deep red vapors is correct.

4. **Dissolving in Aqueous NaOH**:
- When the deep red vapors (CrO2Cl2) are dissolved in aqueous NaOH, they form a yellow solution due to the formation of chromate ions (CrO4^2-). This verifies that the second statement is also correct.

5. **Checking for Greenish Yellow Gas**:
- The third statement mentions the liberation of a greenish-yellow gas. However, during this reaction, only the deep reddish vapor of chromyl chloride is produced, and no greenish-yellow gas is liberated. Therefore, this statement is incorrect.

6. **Dissolving in Water**:
- When the deep red vapor (CrO2Cl2) is dissolved in water, it forms a yellow solution of chromic acid (H2CrO4) along with hydrochloric acid (HCl). This confirms that the fourth statement is also correct.

### Conclusion:
Based on the analysis:
- **Correct Statements**: 1, 2, and 4
- **Incorrect Statement**: 3