Which of the following soled salt on heating with solid `K_(2)Cr_(2)O_(7)` and conc. `H_(2)SO_(4)` orange red vapours are evolved which turn aquous NaOH solution yellow?

Options

A. `NaBr`
B. `NaCl`
C. `NaNO_(3)`
D. `NaI`

Explanation

To solve the question, we need to determine which solid salt, when heated with solid \( K_2Cr_2O_7 \) and concentrated \( H_2SO_4 \), produces orange-red vapors that turn an aqueous \( NaOH \) solution yellow.

### Step-by-Step Solution:

1. **Identify the Reaction**:
We are looking for a solid salt that reacts with \( K_2Cr_2O_7 \) (potassium dichromate) and concentrated \( H_2SO_4 \) (sulfuric acid) to produce orange-red vapors.

2. **Consider Possible Salts**:
The salts to consider are sodium bromide (\( NaBr \)), sodium chloride (\( NaCl \)), sodium nitrate (\( NaNO_3 \)), and sodium iodide (\( NaI \)).

3. **Reaction of Sodium Chloride**:
Let's focus on sodium chloride (\( NaCl \)). When \( NaCl \) is heated with \( K_2Cr_2O_7 \) and concentrated \( H_2SO_4 \), the following reaction occurs:
\[ 6 NaCl + K_2Cr_2O_7 + 3 H_2SO_4 \rightarrow 2 CrO_2Cl_2 + 3 NaHSO_4 + KHSO_4 + 3 H_2O \]
Here, \( CrO_2Cl_2 \) (chromyl chloride) is produced, which is known to give orange-red vapors.

4. **Effect on Aqueous NaOH**:
The next step is to see how these orange-red vapors interact with aqueous \( NaOH \):
\[ CrO_2Cl_2 + 2 NaOH \rightarrow Na_2CrO_4 + 2 NaCl + H_2O \]
The product \( Na_2CrO_4 \) (sodium chromate) is yellow in color.

5. **Conclusion**:
Since the reaction of sodium chloride with \( K_2Cr_2O_7 \) and concentrated \( H_2SO_4 \) produces orange-red vapors that turn an aqueous \( NaOH \) solution yellow, the correct answer is \( NaCl \) (sodium chloride).

### Final Answer:
The required solid salt is **sodium chloride (NaCl)**.