A mixture upon along adding conc. `H_(2)SO_(4)` gives deep red fumes. It may contain the anions pair `:`

Options

A. `Cr_(2)O_(7)^(2-)` and `Cl^(-)`
B. `Br^(-)` and `Cr_(2)O_(7)^(2-)`
C. `NO_(3)^(-)` and `Cl^(-)`
D. `CrO_(4)^(2-)` and `NO_(3)^(-)`

Explanation

To solve the problem of identifying the anion pair that produces deep red fumes upon the addition of concentrated sulfuric acid (H₂SO₄), we can follow these steps:

### Step 1: Understand the Reaction
When concentrated H₂SO₄ is added to certain anions, it can lead to the formation of gaseous products that may exhibit characteristic colors. In this case, we are looking for a reaction that produces deep red fumes.

**Hint:** Consider the behavior of halides and chromates when treated with strong acids.

### Step 2: Identify Possible Anions
The question suggests that the mixture may contain anions. Common anions that react with concentrated H₂SO₄ include chloride (Cl⁻) and chromate (Cr₂O₇²⁻).

**Hint:** Think about the reactions of halides and chromates with concentrated sulfuric acid.

### Step 3: Write the Reaction
When chloride ions (Cl⁻) are mixed with potassium dichromate (K₂Cr₂O₇) and concentrated H₂SO₄, a reaction occurs that produces dichlorine oxide (CrO₂Cl₂), which is responsible for the deep red fumes.

The balanced chemical reaction can be represented as:
\[ 4 \text{Cl}^- + \text{K}_2\text{Cr}_2\text{O}_7 + 6 \text{H}^+ \rightarrow 2 \text{CrO}_2\text{Cl}_2 + 3 \text{H}_2\text{O} \]

**Hint:** Make sure to balance the equation properly to account for all reactants and products.

### Step 4: Conclude the Anion Pair
From the reaction, we can conclude that the anion pair responsible for producing deep red fumes when concentrated H₂SO₄ is added consists of chromate ions (Cr₂O₇²⁻) and chloride ions (Cl⁻).

**Hint:** Look for the specific ions that were involved in the reaction and their respective colors.

### Final Answer
The correct anion pair that produces deep red fumes upon the addition of concentrated H₂SO₄ is:
**Chromate ion (Cr₂O₇²⁻) and Chloride ion (Cl⁻)**.